[gjs/ewlsh/text-encoding] Implement WHATWG Encoding specification.




commit 6f2b8a858a4e0ba776d62acaa3d10afb18d6445b
Author: Evan Welsh <noreply evanwelsh com>
Date:   Mon Nov 23 14:06:20 2020 -0600

    Implement WHATWG Encoding specification.

 .eslintignore                        |    2 +
 .eslintrc.yml                        |    3 +-
 gjs/byteArray.cpp                    |  273 +-------
 gjs/context.cpp                      |    3 +
 gjs/jsapi-util-string.cpp            |   42 ++
 gjs/jsapi-util.h                     |    6 +
 gjs/textEncoding.cpp                 |  472 ++++++++++++++
 gjs/textEncoding.h                   |   32 +
 installed-tests/js/meson.build       |    1 +
 installed-tests/js/testEncoding.js   | 1147 ++++++++++++++++++++++++++++++++++
 js.gresource.xml                     |    2 +
 meson.build                          |    1 +
 modules/core/_encodings.js           |  280 +++++++++
 modules/core/_text.js                |  127 ++++
 modules/core/overrides/GLib.js       |    5 +-
 modules/script/_bootstrap/default.js |   13 +
 modules/script/byteArray.js          |   48 +-
 17 files changed, 2195 insertions(+), 262 deletions(-)
---
diff --git a/.eslintignore b/.eslintignore
index 9ee950d3..8f8f93ff 100644
--- a/.eslintignore
+++ b/.eslintignore
@@ -3,4 +3,6 @@
 
 installed-tests/js/jasmine.js
 installed-tests/js/modules/badOverrides/WarnLib.js
+# Until ESLint merges class fields.
+modules/core/_text.js
 modules/script/jsUnit.js
diff --git a/.eslintrc.yml b/.eslintrc.yml
index 0aa6acf2..c88b2e42 100644
--- a/.eslintrc.yml
+++ b/.eslintrc.yml
@@ -71,7 +71,6 @@ rules:
   jsdoc/newline-after-description: error
   jsdoc/require-jsdoc: error
   jsdoc/require-param: error
-  jsdoc/require-param-description: error
   jsdoc/require-param-name: error
   jsdoc/require-param-type: error
   key-spacing:
@@ -252,5 +251,7 @@ globals:
   print: readonly
   printerr: readonly
   window: readonly
+  TextEncoder: readonly
+  TextDecoder: readonly
 parserOptions:
   ecmaVersion: 2020
diff --git a/gjs/byteArray.cpp b/gjs/byteArray.cpp
index b1d27241..29b07765 100644
--- a/gjs/byteArray.cpp
+++ b/gjs/byteArray.cpp
@@ -5,7 +5,6 @@
 #include <config.h>
 
 #include <stdint.h>
-#include <string.h>  // for strcmp, memchr, strlen
 
 #include <girepository.h>
 #include <glib-object.h>
@@ -13,7 +12,6 @@
 
 #include <js/ArrayBuffer.h>
 #include <js/CallArgs.h>
-#include <js/GCAPI.h>  // for AutoCheckCannotGC
 #include <js/PropertySpec.h>
 #include <js/RootingAPI.h>
 #include <js/TypeDecls.h>
@@ -28,137 +26,16 @@
 #include "gjs/deprecation.h"
 #include "gjs/jsapi-util-args.h"
 #include "gjs/jsapi-util.h"
+#include "gjs/textEncoding.h"
 
 /* Callbacks to use with JS::NewExternalArrayBuffer() */
 
-static void gfree_arraybuffer_contents(void* contents, void*) {
-    g_free(contents);
-}
-
 static void bytes_unref_arraybuffer(void* contents [[maybe_unused]],
                                     void* user_data) {
     auto* gbytes = static_cast<GBytes*>(user_data);
     g_bytes_unref(gbytes);
 }
 
-GJS_JSAPI_RETURN_CONVENTION
-bool to_string_impl_slow(JSContext* cx, uint8_t* data, uint32_t len,
-                         const char* encoding, JS::MutableHandleValue rval) {
-    size_t bytes_written;
-    GError* error = nullptr;
-    GjsAutoChar u16_str = g_convert(reinterpret_cast<char*>(data), len,
-    // Make sure the bytes of the UTF-16 string are laid out in memory
-    // such that we can simply reinterpret_cast<char16_t> them.
-#if G_BYTE_ORDER == G_LITTLE_ENDIAN
-                                    "UTF-16LE",
-#else
-                                    "UTF-16BE",
-#endif
-                                    encoding, nullptr, /* bytes read */
-                                    &bytes_written, &error);
-    if (!u16_str)
-        return gjs_throw_gerror_message(cx, error);  // frees GError
-
-    // bytes_written should be bytes in a UTF-16 string so should be a multiple
-    // of 2
-    g_assert((bytes_written % 2) == 0);
-
-    // g_convert 0-terminates the string, although the 0 isn't included in
-    // bytes_written
-    JSString* s =
-        JS_NewUCStringCopyZ(cx, reinterpret_cast<char16_t*>(u16_str.get()));
-    if (!s)
-        return false;
-
-    rval.setString(s);
-    return true;
-}
-
-/* implement toString() with an optional encoding arg */
-GJS_JSAPI_RETURN_CONVENTION
-static bool to_string_impl(JSContext* context, JS::HandleObject byte_array,
-                           const char* encoding, JS::MutableHandleValue rval) {
-    if (!JS_IsUint8Array(byte_array)) {
-        gjs_throw(context,
-                  "Argument to ByteArray.toString() must be a Uint8Array");
-        return false;
-    }
-
-    bool encoding_is_utf8;
-    uint8_t* data;
-
-    if (encoding) {
-        /* maybe we should be smarter about utf8 synonyms here.
-         * doesn't matter much though. encoding_is_utf8 is
-         * just an optimization anyway.
-         */
-        encoding_is_utf8 = (strcmp(encoding, "UTF-8") == 0);
-    } else {
-        encoding_is_utf8 = true;
-    }
-
-    uint32_t len;
-    bool is_shared_memory;
-    js::GetUint8ArrayLengthAndData(byte_array, &len, &is_shared_memory, &data);
-
-    if (len == 0) {
-        rval.setString(JS_GetEmptyString(context));
-        return true;
-    }
-
-    if (!encoding_is_utf8)
-        return to_string_impl_slow(context, data, len, encoding, rval);
-
-    // optimization, avoids iconv overhead and runs libmozjs hardwired
-    // utf8-to-utf16
-
-    // If there are any 0 bytes, including the terminating byte, stop at the
-    // first one
-    if (data[len - 1] == 0 || memchr(data, 0, len)) {
-        if (!gjs_string_from_utf8(context, reinterpret_cast<char*>(data), rval))
-            return false;
-    } else {
-        if (!gjs_string_from_utf8_n(context, reinterpret_cast<char*>(data), len,
-                                    rval))
-            return false;
-    }
-
-    uint8_t* current_data;
-    uint32_t current_len;
-    bool ignore_val;
-
-    // If a garbage collection occurs between when we call
-    // js::GetUint8ArrayLengthAndData and return from gjs_string_from_utf8, a
-    // use-after-free corruption can occur if the garbage collector shifts the
-    // location of the Uint8Array's private data. To mitigate this we call
-    // js::GetUint8ArrayLengthAndData again and then compare if the length and
-    // pointer are still the same. If the pointers differ, we use the slow path
-    // to ensure no data corruption occurred. The shared-ness of an array cannot
-    // change between calls, so we ignore it.
-    js::GetUint8ArrayLengthAndData(byte_array, &current_len, &ignore_val,
-                                   &current_data);
-
-    // Ensure the private data hasn't changed
-    if (current_len == len && current_data == data)
-        return true;
-
-    // This was the UTF-8 optimized path, so we explicitly pass the encoding
-    return to_string_impl_slow(context, current_data, current_len, "UTF-8",
-                               rval);
-}
-
-GJS_JSAPI_RETURN_CONVENTION
-static bool to_string_func(JSContext* cx, unsigned argc, JS::Value* vp) {
-    JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
-    JS::UniqueChars encoding;
-    JS::RootedObject byte_array(cx);
-
-    if (!gjs_parse_call_args(cx, "toString", args, "o|s", "byteArray",
-                             &byte_array, "encoding", &encoding))
-        return false;
-
-    return to_string_impl(cx, byte_array, encoding.get(), args.rval());
-}
 
 /* Workaround to keep existing code compatible. This function is tacked onto
  * any Uint8Array instances created in situations where previously a ByteArray
@@ -175,144 +52,33 @@ static bool instance_to_string_func(JSContext* cx, unsigned argc,
     if (!gjs_parse_call_args(cx, "toString", args, "|s", "encoding", &encoding))
         return false;
 
-    return to_string_impl(cx, this_obj, encoding.get(), args.rval());
-}
-
-GJS_JSAPI_RETURN_CONVENTION
-static bool
-to_gbytes_func(JSContext *context,
-               unsigned   argc,
-               JS::Value *vp)
-{
-    JS::CallArgs rec = JS::CallArgsFromVp(argc, vp);
-    GIBaseInfo *gbytes_info;
-    JS::RootedObject byte_array(context);
-
-    if (!gjs_parse_call_args(context, "toGBytes", rec, "o",
-                             "byteArray", &byte_array))
-        return false;
-
-    if (!JS_IsUint8Array(byte_array)) {
-        gjs_throw(context,
-                  "Argument to ByteArray.toGBytes() must be a Uint8Array");
+    if (!JS_IsUint8Array(this_obj)) {
+        gjs_throw(cx, "Argument to ByteArray.toString() must be a Uint8Array");
         return false;
     }
 
-    GBytes* bytes = gjs_byte_array_get_bytes(byte_array);
-
-    g_irepository_require(nullptr, "GLib", "2.0", GIRepositoryLoadFlags(0),
-                          nullptr);
-    gbytes_info = g_irepository_find_by_gtype(NULL, G_TYPE_BYTES);
-    JSObject* ret_bytes_obj =
-        BoxedInstance::new_for_c_struct(context, gbytes_info, bytes);
-    g_bytes_unref(bytes);
-    if (!ret_bytes_obj)
-        return false;
-
-    rec.rval().setObject(*ret_bytes_obj);
-    return true;
+    return gjs_decode_from_uint8array(cx, this_obj, encoding.get(), true,
+                                      args.rval());
 }
 
-/* fromString() function implementation */
-GJS_JSAPI_RETURN_CONVENTION
-static bool
-from_string_func(JSContext *context,
-                 unsigned   argc,
-                 JS::Value *vp)
-{
-    JS::CallArgs argv = JS::CallArgsFromVp (argc, vp);
-    JS::UniqueChars encoding;
-    JS::UniqueChars utf8;
-    bool encoding_is_utf8;
-    JS::RootedObject obj(context), array_buffer(context);
-
-    if (!gjs_parse_call_args(context, "fromString", argv, "s|s",
-                             "string", &utf8,
-                             "encoding", &encoding))
-        return false;
-
-    if (argc > 1) {
-        /* maybe we should be smarter about utf8 synonyms here.
-         * doesn't matter much though. encoding_is_utf8 is
-         * just an optimization anyway.
-         */
-        encoding_is_utf8 = (strcmp(encoding.get(), "UTF-8") == 0);
-    } else {
-        encoding_is_utf8 = true;
-    }
-
-    if (encoding_is_utf8) {
-        /* optimization? avoids iconv overhead and runs
-         * libmozjs hardwired utf16-to-utf8.
-         */
-        size_t len = strlen(utf8.get());
-        array_buffer =
-            JS::NewArrayBufferWithContents(context, len, utf8.release());
-    } else {
-        JSString *str = argv[0].toString();  /* Rooted by argv */
-        GError *error = NULL;
-        char *encoded = NULL;
-        gsize bytes_written;
-
-        /* Scope for AutoCheckCannotGC, will crash if a GC is triggered
-         * while we are using the string's chars */
-        {
-            JS::AutoCheckCannotGC nogc;
-            size_t len;
-
-            if (JS_StringHasLatin1Chars(str)) {
-                const JS::Latin1Char *chars =
-                    JS_GetLatin1StringCharsAndLength(context, nogc, str, &len);
-                if (chars == NULL)
-                    return false;
-
-                encoded = g_convert((char *) chars, len,
-                                    encoding.get(),  // to_encoding
-                                    "LATIN1",  /* from_encoding */
-                                    NULL,  /* bytes read */
-                                    &bytes_written, &error);
-            } else {
-                const char16_t *chars =
-                    JS_GetTwoByteStringCharsAndLength(context, nogc, str, &len);
-                if (chars == NULL)
-                    return false;
-
-                encoded = g_convert((char *) chars, len * 2,
-                                    encoding.get(),  // to_encoding
-                                    "UTF-16",  /* from_encoding */
-                                    NULL,  /* bytes read */
-                                    &bytes_written, &error);
-            }
-        }
-
-        if (!encoded)
-            return gjs_throw_gerror_message(context, error);  // frees GError
-
-        array_buffer =
-            JS::NewExternalArrayBuffer(context, bytes_written, encoded,
-                                       gfree_arraybuffer_contents, nullptr);
-    }
+static bool define_to_string_func(JSContext* cx, unsigned argc, JS::Value* vp) {
+    const GjsAtoms& atoms = GjsContextPrivate::atoms(cx);
+    JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
+    JS::RootedObject obj(cx);
 
-    if (!array_buffer)
+    if (!gjs_parse_call_args(cx, "defineToString", args, "o", "obj", &obj))
         return false;
-    obj = JS_NewUint8ArrayWithBuffer(context, array_buffer, 0, -1);
 
-    const GjsAtoms& atoms = GjsContextPrivate::atoms(context);
-    if (!JS_DefineFunctionById(context, obj, atoms.to_string(),
+    if (!JS_DefineFunctionById(cx, obj, atoms.to_string(),
                                instance_to_string_func, 1, 0))
         return false;
 
-    argv.rval().setObject(*obj);
     return true;
 }
 
 GJS_JSAPI_RETURN_CONVENTION
-static bool
-from_gbytes_func(JSContext *context,
-                 unsigned   argc,
-                 JS::Value *vp)
-{
-    JS::CallArgs argv = JS::CallArgsFromVp (argc, vp);
+static bool from_gbytes_func(JSContext* context, unsigned argc, JS::Value* vp) {
+    JS::CallArgs argv = JS::CallArgsFromVp(argc, vp);
     JS::RootedObject bytes_obj(context);
     GBytes *gbytes;
 
@@ -392,16 +158,11 @@ GByteArray* gjs_byte_array_get_byte_array(JSObject* obj) {
 }
 
 static JSFunctionSpec gjs_byte_array_module_funcs[] = {
-    JS_FN("fromString", from_string_func, 2, 0),
     JS_FN("fromGBytes", from_gbytes_func, 1, 0),
-    JS_FN("toGBytes", to_gbytes_func, 1, 0),
-    JS_FN("toString", to_string_func, 2, 0),
-    JS_FS_END};
-
-bool
-gjs_define_byte_array_stuff(JSContext              *cx,
-                            JS::MutableHandleObject module)
-{
+    JS_FN("defineToString", define_to_string_func, 1, 0), JS_FS_END};
+
+bool gjs_define_byte_array_stuff(JSContext* cx,
+                                 JS::MutableHandleObject module) {
     module.set(JS_NewPlainObject(cx));
     return JS_DefineFunctions(cx, module, gjs_byte_array_module_funcs);
 }
diff --git a/gjs/context.cpp b/gjs/context.cpp
index 59310a69..e8963844 100644
--- a/gjs/context.cpp
+++ b/gjs/context.cpp
@@ -75,6 +75,7 @@
 #include "gjs/objectbox.h"
 #include "gjs/profiler-private.h"
 #include "gjs/profiler.h"
+#include "gjs/textEncoding.h"
 #include "modules/modules.h"
 #include "util/log.h"
 
@@ -313,6 +314,8 @@ gjs_context_class_init(GjsContextClass *klass)
     }
 
     gjs_register_native_module("_byteArrayNative", gjs_define_byte_array_stuff);
+    gjs_register_native_module("_encodingNative",
+                               gjs_define_text_encoding_stuff);
     gjs_register_native_module("_gi", gjs_define_private_gi_stuff);
     gjs_register_native_module("gi", gjs_define_repo);
 
diff --git a/gjs/jsapi-util-string.cpp b/gjs/jsapi-util-string.cpp
index 28182cec..09ad5914 100644
--- a/gjs/jsapi-util-string.cpp
+++ b/gjs/jsapi-util-string.cpp
@@ -74,6 +74,48 @@ JS::UniqueChars gjs_string_to_utf8(JSContext* cx, const JS::Value value) {
     return JS_EncodeStringToUTF8(cx, str);
 }
 
+bool gjs_lossy_string_from_utf8(JSContext* cx, const char* utf8_string,
+                                JS::MutableHandleValue value_p) {
+    JS::ConstUTF8CharsZ chars(utf8_string, strlen(utf8_string));
+    size_t len;
+    JS::UniqueTwoByteChars twobyte_chars(
+        JS::LossyUTF8CharsToNewTwoByteCharsZ(cx, chars, &len, js::MallocArena)
+            .get());
+
+    if (!twobyte_chars) {
+        return false;
+    }
+
+    JS::RootedString str(cx, JS_NewUCStringCopyN(cx, twobyte_chars.get(), len));
+
+    if (str)
+        value_p.setString(str);
+
+    return str != nullptr;
+}
+bool gjs_lossy_string_from_utf8_n(JSContext* cx, const char* utf8_string,
+                                  size_t len, JS::MutableHandleValue value_p) {
+    JS::UTF8Chars chars(utf8_string, len);
+    size_t outlen;
+
+    JS::UniqueTwoByteChars twobyte_chars(
+        JS::LossyUTF8CharsToNewTwoByteCharsZ(cx, chars, &outlen,
+                                             js::MallocArena)
+            .get());
+
+    if (!twobyte_chars) {
+        return false;
+    }
+
+    JS::RootedString str(cx,
+                         JS_NewUCStringCopyN(cx, twobyte_chars.get(), outlen));
+
+    if (str)
+        value_p.setString(str);
+
+    return str != nullptr;
+}
+
 bool
 gjs_string_from_utf8(JSContext             *context,
                      const char            *utf8_string,
diff --git a/gjs/jsapi-util.h b/gjs/jsapi-util.h
index 11c23776..43b8f4df 100644
--- a/gjs/jsapi-util.h
+++ b/gjs/jsapi-util.h
@@ -431,6 +431,12 @@ void gjs_warning_reporter(JSContext*, JSErrorReport* report);
 GJS_JSAPI_RETURN_CONVENTION
 JS::UniqueChars gjs_string_to_utf8(JSContext* cx, const JS::Value string_val);
 GJS_JSAPI_RETURN_CONVENTION
+bool gjs_lossy_string_from_utf8(JSContext* context, const char* utf8_string,
+                                JS::MutableHandleValue value_p);
+GJS_JSAPI_RETURN_CONVENTION
+bool gjs_lossy_string_from_utf8_n(JSContext* context, const char* utf8_string,
+                                  size_t len, JS::MutableHandleValue value_p);
+GJS_JSAPI_RETURN_CONVENTION
 bool gjs_string_from_utf8(JSContext             *context,
                           const char            *utf8_string,
                           JS::MutableHandleValue value_p);
diff --git a/gjs/textEncoding.cpp b/gjs/textEncoding.cpp
new file mode 100644
index 00000000..743a79d6
--- /dev/null
+++ b/gjs/textEncoding.cpp
@@ -0,0 +1,472 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil; -*- */
+// SPDX-License-Identifier: MIT OR LGPL-2.0-or-later
+// SPDX-FileCopyrightText: 2010 litl, LLC
+// SPDX-FileCopyrightText: 2020 Evan Welsh
+
+#include <config.h>
+
+#include <stdint.h>
+#include <string.h>  // for strcmp, memchr, strlen
+
+#include <algorithm>
+#include <vector>
+
+#include <gio/gio.h>
+#include <girepository.h>
+#include <glib-object.h>
+#include <glib.h>
+
+#include <js/ArrayBuffer.h>
+#include <js/CallArgs.h>
+#include <js/CharacterEncoding.h>
+#include <js/GCAPI.h>  // for AutoCheckCannotGC
+#include <js/PropertySpec.h>
+#include <js/RootingAPI.h>
+#include <js/TypeDecls.h>
+#include <js/Utility.h>   // for UniqueChars
+#include <jsapi.h>        // for JS_DefineFunctionById, JS_DefineFun...
+#include <jsfriendapi.h>  // for JS_NewUint8ArrayWithBuffer, GetUint...
+
+#include "gi/boxed.h"
+#include "gjs/atoms.h"
+#include "gjs/context-private.h"
+#include "gjs/deprecation.h"
+#include "gjs/jsapi-util-args.h"
+#include "gjs/jsapi-util.h"
+#include "gjs/textEncoding.h"
+
+static void gfree_arraybuffer_contents(void* contents, void*) {
+    g_free(contents);
+}
+
+static const char* FALLBACK = "\ufffd";
+static size_t FALLBACK_LEN = strlen(FALLBACK);
+
+GJS_JSAPI_RETURN_CONVENTION
+static bool gjs_convert_invalid_input(JSContext* cx, uint8_t* data, size_t len,
+                                      const char* to_codeset,
+                                      const char* from_codeset,
+                                      char** converted) {
+    GError* error = nullptr;
+    GjsAutoUnref<GCharsetConverter> converter(
+        g_charset_converter_new(to_codeset, from_codeset, &error));
+
+    // This should only throw if an encoding is not available.
+    if (error)
+        return gjs_throw_gerror_message(cx, error);
+
+    size_t bytes_written, bytes_read;
+    char buffer[1024];
+
+    // Cast data to convert input type, calculate length.
+    const char* input = reinterpret_cast<const char*>(data);
+    size_t input_len = len * sizeof(char);
+
+    // Use a vector for the output for easy resizing.
+    std::vector<char> output;
+    size_t size = 0;
+
+    do {
+        g_converter_convert(G_CONVERTER(converter.get()), input, input_len,
+                            buffer, sizeof(buffer), G_CONVERTER_INPUT_AT_END,
+                            &bytes_read, &bytes_written, &error);
+
+        input += bytes_read;
+        input_len -= bytes_read;
+
+        if (bytes_written > 0) {
+            output.resize(size + bytes_written);
+            std::copy(buffer, buffer + bytes_written, output.data() + size);
+            size += bytes_written;
+        }
+
+        if (error) {
+            if (g_error_matches(error, G_IO_ERROR, G_IO_ERROR_INVALID_DATA)) {
+                // Skip the invalid character
+                input += sizeof(char);
+                input_len -= sizeof(char);
+
+                // Append fallback character to the output
+                output.resize(size + FALLBACK_LEN);
+                std::copy(FALLBACK, FALLBACK + FALLBACK_LEN,
+                          output.data() + size);
+                size += FALLBACK_LEN;
+
+                g_clear_error(&error);
+            } else if (bytes_written > 0 &&
+                       g_error_matches(error, G_IO_ERROR,
+                                       G_IO_ERROR_PARTIAL_INPUT)) {
+                // Only clear a partial input error if there are no bytes
+                // written. This occurs on the second loop, otherwise we could
+                // error mid-input.
+                g_clear_error(&error);
+            } else if (g_error_matches(error, G_IO_ERROR,
+                                       G_IO_ERROR_NO_SPACE)) {
+                // If the buffer was full, clear the error and continue
+                // converting.
+                g_clear_error(&error);
+            }
+        }
+    } while (input_len && !error);
+
+    if (!error) {
+        char* arr = reinterpret_cast<char*>(g_malloc0(output.size()));
+
+        std::copy(output.begin(), output.end(), arr);
+
+        *converted = arr;
+
+        // bytes_written should be bytes in a UTF-16 string so should be a
+        // multiple of 2
+        g_assert((bytes_written % 2) == 0);
+
+        return true;
+    }
+
+    return gjs_throw_gerror_message(cx, error);
+}
+
+GJS_JSAPI_RETURN_CONVENTION
+bool gjs_decode_from_uint8array_slow(JSContext* cx, uint8_t* data, uint32_t len,
+                                     const char* encoding, bool fatal,
+                                     JS::MutableHandleValue rval) {
+    size_t bytes_written, bytes_read;
+    GError* error = nullptr;
+    GjsAutoChar u16_str;
+
+// Make sure the bytes of the UTF-16 string are laid out in memory
+// such that we can simply reinterpret_cast<char16_t> them.
+#if G_BYTE_ORDER == G_LITTLE_ENDIAN
+    const char* to_codeset = "UTF-16LE";
+#else
+    const char* to_codeset = "UTF-16BE";
+#endif
+
+    if (fatal) {
+        u16_str = g_convert(reinterpret_cast<char*>(data), len, to_codeset,
+                            encoding, nullptr, /* bytes read */
+                            &bytes_written, &error);
+
+        // bytes_written should be bytes in a UTF-16 string so should be a
+        // multiple of 2
+        g_assert((bytes_written % 2) == 0);
+    } else {
+        // This will fail if the input contains invalid codepoints in the
+        // from_codeset. It inserts a replacement character if the input is
+        // valid but can't be represented in the output.
+        u16_str = g_convert_with_fallback(reinterpret_cast<char*>(data), len,
+                                          to_codeset, encoding, FALLBACK,
+                                          &bytes_read, &bytes_written, &error);
+
+        if (u16_str) {
+            g_assert((bytes_written % 2) == 0);
+        }
+
+        // If the input is invalid we need to do the conversion ourselves.
+        if (error && g_error_matches(error, G_CONVERT_ERROR,
+                                     G_CONVERT_ERROR_ILLEGAL_SEQUENCE)) {
+            // Clear the illegal sequence error.
+            g_clear_error(&error);
+
+            char* str;
+
+            if (!gjs_convert_invalid_input(cx, data, len, to_codeset, encoding,
+                                           &str)) {
+                return false;
+            }
+
+            u16_str = str;
+        }
+    }
+
+    if (error) {
+        return gjs_throw_gerror_message(cx, error);
+    }
+
+    // g_convert 0-terminates the string, although the 0 isn't included in
+    // bytes_written
+    JSString* s =
+        JS_NewUCStringCopyZ(cx, reinterpret_cast<char16_t*>(u16_str.get()));
+    if (!s)
+        return false;
+
+    rval.setString(s);
+    return true;
+}
+
+inline bool is_utf8_label(const char* encoding) {
+    if (encoding) {
+        /* maybe we should be smarter about utf8 synonyms here.
+         * doesn't matter much though. encoding_is_utf8 is
+         * just an optimization anyway.
+         */
+        if (strcasecmp(encoding, "utf-8") == 0) {
+            return true;
+        } else {
+            GjsAutoChar stripped(g_strdup(encoding));
+            return (strcasecmp(g_strstrip(stripped), "utf-8") == 0);
+        }
+    } else {
+        return true;
+    }
+}
+
+GJS_JSAPI_RETURN_CONVENTION
+bool gjs_decode_from_uint8array(JSContext* cx, JS::HandleObject uint8array,
+                                const char* encoding, bool fatal,
+                                JS::MutableHandleValue rval) {
+    if (!JS_IsUint8Array(uint8array)) {
+        gjs_throw(
+            cx, "Argument to gjs_decode_from_uint8array must be a Uint8Array");
+        return false;
+    }
+
+    bool encoding_is_utf8 = is_utf8_label(encoding);
+    uint8_t* data;
+
+    uint32_t len;
+    bool is_shared_memory;
+    js::GetUint8ArrayLengthAndData(uint8array, &len, &is_shared_memory, &data);
+
+    if (len == 0) {
+        rval.setString(JS_GetEmptyString(cx));
+        return true;
+    }
+
+    if (!encoding_is_utf8)
+        return gjs_decode_from_uint8array_slow(cx, data, len, encoding, fatal,
+                                               rval);
+
+    // optimization, avoids iconv overhead and runs libmozjs hardwired
+    // utf8-to-utf16
+
+    // If there are any 0 bytes, including the terminating byte, stop at the
+    // first one
+    if (data[len - 1] == 0 || memchr(data, 0, len)) {
+        if (fatal) {
+            if (!gjs_string_from_utf8(cx, reinterpret_cast<char*>(data), rval))
+                return false;
+        } else {
+            if (!gjs_lossy_string_from_utf8(cx, reinterpret_cast<char*>(data),
+                                            rval))
+                return false;
+        }
+    } else {
+        if (fatal) {
+            if (!gjs_string_from_utf8_n(cx, reinterpret_cast<char*>(data), len,
+                                        rval))
+                return false;
+        } else {
+            if (!gjs_lossy_string_from_utf8_n(cx, reinterpret_cast<char*>(data),
+                                              len, rval))
+                return false;
+        }
+    }
+
+    uint8_t* current_data;
+    uint32_t current_len;
+    bool ignore_val;
+
+    // If a garbage collection occurs between when we call
+    // js::GetUint8ArrayLengthAndData and return from gjs_string_from_utf8, a
+    // use-after-free corruption can occur if the garbage collector shifts the
+    // location of the Uint8Array's private data. To mitigate this we call
+    // js::GetUint8ArrayLengthAndData again and then compare if the length and
+    // pointer are still the same. If the pointers differ, we use the slow path
+    // to ensure no data corruption occurred. The shared-ness of an array cannot
+    // change between calls, so we ignore it.
+    js::GetUint8ArrayLengthAndData(uint8array, &current_len, &ignore_val,
+                                   &current_data);
+
+    // Ensure the private data hasn't changed
+    if (current_len == len && current_data == data)
+        return true;
+
+    // This was the UTF-8 optimized path, so we explicitly pass the encoding
+    return gjs_decode_from_uint8array_slow(cx, current_data, current_len,
+                                           "UTF-8", fatal, rval);
+}
+
+GJS_JSAPI_RETURN_CONVENTION
+static bool Decode(JSContext* cx, unsigned argc, JS::Value* vp) {
+    JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
+    JS::UniqueChars encoding;
+    bool fatal = false;
+    JS::RootedObject uint8array(cx);
+
+    if (!gjs_parse_call_args(cx, "toString", args, "o|bs", "uint8array",
+                             &uint8array, "fatal", &fatal, "encoding",
+                             &encoding))
+        return false;
+
+    return gjs_decode_from_uint8array(cx, uint8array, encoding.get(), fatal,
+                                      args.rval());
+}
+
+/* fromString() function implementation */
+GJS_JSAPI_RETURN_CONVENTION
+bool gjs_encode_to_uint8array(JSContext* cx, JS::HandleString str,
+                              const char* encoding,
+                              JS::MutableHandleValue rval) {
+    bool encoding_is_utf8 = is_utf8_label(encoding);
+
+    JS::UniqueChars utf8 = JS_EncodeStringToUTF8(cx, str);
+    JS::RootedObject obj(cx), array_buffer(cx);
+
+    if (encoding_is_utf8) {
+        /* optimization? avoids iconv overhead and runs
+         * libmozjs hardwired utf16-to-utf8.
+         */
+        size_t len = strlen(utf8.get());
+        array_buffer = JS::NewArrayBufferWithContents(cx, len, utf8.release());
+    } else {
+        GError* error = nullptr;
+        char* encoded = nullptr;
+        gsize bytes_written;
+
+        /* Scope for AutoCheckCannotGC, will crash if a GC is triggered
+         * while we are using the string's chars */
+        {
+            JS::AutoCheckCannotGC nogc;
+            size_t len;
+
+            if (JS_StringHasLatin1Chars(str)) {
+                const JS::Latin1Char* chars =
+                    JS_GetLatin1StringCharsAndLength(cx, nogc, str, &len);
+                if (chars == NULL)
+                    return false;
+
+                encoded = g_convert(reinterpret_cast<const char*>(chars), len,
+                                    encoding,  // to_encoding
+                                    "LATIN1",  /* from_encoding */
+                                    NULL,      /* bytes read */
+                                    &bytes_written, &error);
+            } else {
+                const char16_t* chars =
+                    JS_GetTwoByteStringCharsAndLength(cx, nogc, str, &len);
+                if (chars == NULL)
+                    return false;
+
+                encoded =
+                    g_convert(reinterpret_cast<const char*>(chars), len * 2,
+                              encoding,  // to_encoding
+                              "UTF-16",  /* from_encoding */
+                              NULL,      /* bytes read */
+                              &bytes_written, &error);
+            }
+        }
+
+        if (!encoded)
+            return gjs_throw_gerror_message(cx, error);  // frees GError
+
+        array_buffer = JS::NewExternalArrayBuffer(
+            cx, bytes_written, encoded, gfree_arraybuffer_contents, nullptr);
+    }
+
+    if (!array_buffer)
+        return false;
+    obj = JS_NewUint8ArrayWithBuffer(cx, array_buffer, 0, -1);
+
+    rval.setObject(*obj);
+    return true;
+}
+
+GJS_JSAPI_RETURN_CONVENTION
+bool gjs_encode_into_uint8array(JSContext* cx, JS::HandleString str,
+                                JS::HandleObject uint8array,
+                                JS::MutableHandleValue rval) {
+    if (!JS_IsUint8Array(uint8array)) {
+        gjs_throw(
+            cx, "Argument to gjs_encode_into_uint8array must be a Uint8Array");
+        return false;
+    }
+
+    auto len = JS_GetTypedArrayByteLength(uint8array);
+    bool shared;
+
+    // TODO(ewlsh): Garbage collection cannot occur from here...
+    auto data =
+        JS_GetUint8ArrayData(uint8array, &shared, JS::AutoCheckCannotGC(cx));
+
+    if (shared) {
+        gjs_throw(cx, "Cannot encode data into shared memory.");
+        return false;
+    }
+
+    auto maybe = JS_EncodeStringToUTF8BufferPartial(
+        cx, str, mozilla::AsWritableChars(mozilla::Span(data, len)));
+    // ... to here
+
+    if (!maybe) {
+        JS_ReportOutOfMemory(cx);
+        return false;
+    }
+
+    size_t read, written;
+
+    mozilla::Tie(read, written) = *maybe;
+
+    g_assert(written <= len);
+
+    JS::RootedObject result(cx, JS_NewPlainObject(cx));
+    JS::RootedValue readv(cx, JS::NumberValue(read)),
+        writtenv(cx, JS::NumberValue(written));
+
+    if (!JS_SetProperty(cx, result, "read", readv) ||
+        !JS_SetProperty(cx, result, "written", writtenv)) {
+        return false;
+    }
+
+    rval.setObject(*result);
+    return true;
+}
+
+GJS_JSAPI_RETURN_CONVENTION
+static bool Encode(JSContext* cx, unsigned argc, JS::Value* vp) {
+    JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
+    JS::UniqueChars encoding;
+    JS::UniqueChars utf8;
+
+    if (!gjs_parse_call_args(cx, "Encode", args, "s|s", "string", &utf8,
+                             "encoding", &encoding))
+        return false;
+
+    if (!args[0].isString()) {
+        gjs_throw(cx, "First argument to encode() must be a string.");
+        return false;
+    }
+
+    JS::RootedString str(cx, args[0].toString());
+
+    return gjs_encode_to_uint8array(cx, str, encoding.get(), args.rval());
+}
+
+GJS_JSAPI_RETURN_CONVENTION
+static bool EncodeInto(JSContext* cx, unsigned argc, JS::Value* vp) {
+    JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
+    JS::UniqueChars utf8;
+    JS::RootedObject uint8array(cx);
+
+    if (!gjs_parse_call_args(cx, "EncodeInto", args, "so", "string", &utf8,
+                             "uint8array", &uint8array))
+        return false;
+
+    if (!args[0].isString()) {
+        gjs_throw(cx, "First argument to encode() must be a string.");
+        return false;
+    }
+
+    JS::RootedString str(cx, args[0].toString());
+
+    return gjs_encode_into_uint8array(cx, str, uint8array, args.rval());
+}
+
+static JSFunctionSpec gjs_text_encoding_module_funcs[] = {
+    JS_FN("encodeInto", EncodeInto, 2, 0), JS_FN("encode", Encode, 2, 0),
+    JS_FN("decode", Decode, 3, 0), JS_FS_END};
+
+bool gjs_define_text_encoding_stuff(JSContext* cx,
+                                    JS::MutableHandleObject module) {
+    module.set(JS_NewPlainObject(cx));
+    return JS_DefineFunctions(cx, module, gjs_text_encoding_module_funcs);
+}
diff --git a/gjs/textEncoding.h b/gjs/textEncoding.h
new file mode 100644
index 00000000..64e93205
--- /dev/null
+++ b/gjs/textEncoding.h
@@ -0,0 +1,32 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil; -*- */
+// SPDX-License-Identifier: MIT OR LGPL-2.0-or-later
+// SPDX-FileCopyrightText: 2020 Evan Welsh
+
+#ifndef GJS_TEXTENCODING_H_
+#define GJS_TEXTENCODING_H_
+
+#include <config.h>
+
+#include <stddef.h>  // for size_t
+
+#include <glib.h>
+
+#include <js/TypeDecls.h>
+
+#include "gjs/macros.h"
+
+GJS_JSAPI_RETURN_CONVENTION
+bool gjs_decode_from_uint8array(JSContext* cx, JS::HandleObject uint8array,
+                                const char* encoding, bool fatal,
+                                JS::MutableHandleValue rval);
+
+GJS_JSAPI_RETURN_CONVENTION
+bool gjs_encode_to_uint8array(JSContext* cx, JS::HandleString str,
+                              const char* encoding,
+                              JS::MutableHandleValue rval);
+
+GJS_JSAPI_RETURN_CONVENTION
+bool gjs_define_text_encoding_stuff(JSContext* cx,
+                                    JS::MutableHandleObject module);
+
+#endif  // GJS_TEXTENCODING_H_
diff --git a/installed-tests/js/meson.build b/installed-tests/js/meson.build
index 15b17d63..e3d0a88e 100644
--- a/installed-tests/js/meson.build
+++ b/installed-tests/js/meson.build
@@ -92,6 +92,7 @@ gimarshallingtests_typelib = gimarshallingtests_gir[1]
 jasmine_tests = [
     'self',
     'ByteArray',
+    'Encoding',
     'Exceptions',
     'Format',
     'Fundamental',
diff --git a/installed-tests/js/testEncoding.js b/installed-tests/js/testEncoding.js
new file mode 100644
index 00000000..516ac591
--- /dev/null
+++ b/installed-tests/js/testEncoding.js
@@ -0,0 +1,1147 @@
+// SPDX-License-Identifier: MIT OR LGPL-2.0-or-later
+// SPDX-FileCopyrightText: Copyright 2018-2020 the Deno authors. All rights reserved.
+
+// Modified from https://github.com/denoland/deno/blob/master/op_crates/web/text_encoding_test.js
+// Data originally from https://encoding.spec.whatwg.org/encodings.json
+
+describe('Text Encoding', function () {
+    it('textDecoder', function () {
+        const fixture = new Uint8Array([
+            0xf0,
+            0x9d,
+            0x93,
+            0xbd,
+            0xf0,
+            0x9d,
+            0x93,
+            0xae,
+            0xf0,
+            0x9d,
+            0x94,
+            0x81,
+            0xf0,
+            0x9d,
+            0x93,
+            0xbd,
+        ]);
+        const decoder = new TextDecoder();
+        expect(decoder.decode(fixture)).toBe('𝓽𝓮𝔁𝓽');
+    });
+
+    it('textDecoderIgnoreBOM', function () {
+        const fixture = new Uint8Array([
+            0xef,
+            0xbb,
+            0xbf,
+            0xf0,
+            0x9d,
+            0x93,
+            0xbd,
+            0xf0,
+            0x9d,
+            0x93,
+            0xae,
+            0xf0,
+            0x9d,
+            0x94,
+            0x81,
+            0xf0,
+            0x9d,
+            0x93,
+            0xbd,
+        ]);
+        const decoder = new TextDecoder('utf-8', {ignoreBOM: true});
+        expect(decoder.decode(fixture)).toBe('𝓽𝓮𝔁𝓽');
+    });
+
+    it('textDecoderNotBOM', function () {
+        const fixture = new Uint8Array([
+            0xef,
+            0xbb,
+            0x89,
+            0xf0,
+            0x9d,
+            0x93,
+            0xbd,
+            0xf0,
+            0x9d,
+            0x93,
+            0xae,
+            0xf0,
+            0x9d,
+            0x94,
+            0x81,
+            0xf0,
+            0x9d,
+            0x93,
+            0xbd,
+        ]);
+        const decoder = new TextDecoder('utf-8', {ignoreBOM: true});
+        expect(decoder.decode(fixture)).toBe('ﻉ𝓽𝓮𝔁𝓽');
+    });
+
+    it('textDecoderASCII', function () {
+        const fixture = new Uint8Array([0x89, 0x95, 0x9f, 0xbf]);
+        const decoder = new TextDecoder('ascii');
+        expect(decoder.decode(fixture)).toBe('‰•Ÿ¿');
+    });
+
+    it('textDecoderErrorEncoding', function () {
+        expect(() => new TextDecoder('Foo')).toThrowError("Invalid encoding label: 'Foo'");
+    });
+
+    // GJS can handle 'gbk', Deno does not.
+    // it('textDecoderHandlesNotFoundInternalDecoder', function () {
+    //     let didThrow = false;
+    //     try {
+    //         new TextDecoder("gbk");
+    //     } catch (e) {
+    //         didThrow = true;
+    //         expect(e instanceof RangeError).toBe(true);
+    //     }
+    //     expect(didThrow).toBe(true);
+    // });
+
+    it('textDecoderHandlesUndefined', function () {
+        const fixture = undefined;
+        const decoder = new TextDecoder();
+        expect(decoder.decode(fixture)).toBe('');
+    });
+
+    it('textDecoderThrowsOnEmpty', function () {
+        const fixture = '';
+        const decoder = new TextDecoder();
+
+        expect(() => decoder.decode(fixture))
+            .toThrowError('Provided input cannot be converted to ArrayBufferView or ArrayBuffer');
+    });
+
+    it('textDecoderThrowsOnNull', function () {
+        const fixture = null;
+        const decoder = new TextDecoder();
+
+        expect(() => decoder.decode(fixture))
+            .toThrowError('Provided input cannot be converted to ArrayBufferView or ArrayBuffer');
+    });
+
+    it('textEncoder', function () {
+        const fixture = '𝓽𝓮𝔁𝓽';
+        const encoder = new TextEncoder();
+
+        expect(Array.from(encoder.encode(fixture))).toEqual([
+            0xf0,
+            0x9d,
+            0x93,
+            0xbd,
+            0xf0,
+            0x9d,
+            0x93,
+            0xae,
+            0xf0,
+            0x9d,
+            0x94,
+            0x81,
+            0xf0,
+            0x9d,
+            0x93,
+            0xbd,
+        ]);
+    });
+
+    it('textEncodeInto', function () {
+        const fixture = 'text';
+        const encoder = new TextEncoder();
+        const bytes = new Uint8Array(5);
+        const result = encoder.encodeInto(fixture, bytes);
+        expect(result.read).toBe(4);
+        expect(result.written).toBe(4);
+
+        expect(Array.from(bytes)).toEqual([0x74, 0x65, 0x78, 0x74, 0x00]);
+    });
+
+    it('textEncodeInto2', function () {
+        const fixture = '𝓽𝓮𝔁𝓽';
+        const encoder = new TextEncoder();
+        const bytes = new Uint8Array(17);
+        const result = encoder.encodeInto(fixture, bytes);
+        expect(result.read).toBe(8);
+        expect(result.written).toBe(16);
+
+        expect(Array.from(bytes)).toEqual([
+            0xf0,
+            0x9d,
+            0x93,
+            0xbd,
+            0xf0,
+            0x9d,
+            0x93,
+            0xae,
+            0xf0,
+            0x9d,
+            0x94,
+            0x81,
+            0xf0,
+            0x9d,
+            0x93,
+            0xbd,
+            0x00,
+        ]);
+    });
+
+    it('textEncodeInto3', function () {
+        const fixture = '𝓽𝓮𝔁𝓽';
+        const encoder = new TextEncoder();
+        const bytes = new Uint8Array(5);
+        const result = encoder.encodeInto(fixture, bytes);
+        expect(result.read).toBe(2);
+        expect(result.written).toBe(4);
+
+        expect(Array.from(bytes)).toEqual([0xf0, 0x9d, 0x93, 0xbd, 0x00]);
+    });
+
+    // TODO(ewlsh): GJS doesn't support SharedArrayBuffer yet.
+
+    // it('textDecoderSharedUint8Array', function () {
+    //     const ab = new SharedArrayBuffer(6);
+    //     const dataView = new DataView(ab);
+    //     const charCodeA = "A".charCodeAt(0);
+    //     for (let i = 0; i < ab.byteLength; i++) {
+    //         dataView.setUint8(i, charCodeA + i);
+    //     }
+    //     const ui8 = new Uint8Array(ab);
+    //     const decoder = new TextDecoder();
+    //     const actual = decoder.decode(ui8);
+    //     expect(actual).toBe("ABCDEF");
+    // });
+    // it('textDecoderSharedInt32Array', function () {
+    //     const ab = new SharedArrayBuffer(8);
+    //     const dataView = new DataView(ab);
+    //     const charCodeA = "A".charCodeAt(0);
+    //     for (let i = 0; i < ab.byteLength; i++) {
+    //         dataView.setUint8(i, charCodeA + i);
+    //     }
+    //     const i32 = new Int32Array(ab);
+    //     const decoder = new TextDecoder();
+    //     const actual = decoder.decode(i32);
+    //     expect(actual).toBe("ABCDEFGH");
+    // });
+
+    it('toStringShouldBeWebCompatibility', function () {
+        const encoder = new TextEncoder();
+
+        expect(encoder.toString()).toBe('[object TextEncoder]');
+
+        const decoder = new TextDecoder();
+        expect(decoder.toString()).toBe('[object TextDecoder]');
+    });
+
+    it('singleByteEncodings', function () {
+        // Straight from https://encoding.spec.whatwg.org/encodings.json
+        const encodingsTable = [
+            {
+                encodings: [
+                    {
+                        labels: [
+                            'unicode-1-1-utf-8',
+                            'unicode11utf8',
+                            'unicode20utf8',
+                            'utf-8',
+                            'utf8',
+                            'x-unicode20utf8',
+                        ],
+                        name: 'UTF-8',
+                    },
+                ],
+                heading: 'The Encoding',
+            },
+            {
+                encodings: [
+                    {
+                        labels: ['866', 'cp866', 'csibm866', 'ibm866'],
+                        name: 'IBM866',
+                    },
+                    {
+                        labels: [
+                            'csisolatin2',
+                            'iso-8859-2',
+                            'iso-ir-101',
+                            'iso8859-2',
+                            'iso88592',
+                            'iso_8859-2',
+                            'iso_8859-2:1987',
+                            'l2',
+                            'latin2',
+                        ],
+                        name: 'ISO-8859-2',
+                    },
+                    {
+                        labels: [
+                            'csisolatin3',
+                            'iso-8859-3',
+                            'iso-ir-109',
+                            'iso8859-3',
+                            'iso88593',
+                            'iso_8859-3',
+                            'iso_8859-3:1988',
+                            'l3',
+                            'latin3',
+                        ],
+                        name: 'ISO-8859-3',
+                    },
+                    {
+                        labels: [
+                            'csisolatin4',
+                            'iso-8859-4',
+                            'iso-ir-110',
+                            'iso8859-4',
+                            'iso88594',
+                            'iso_8859-4',
+                            'iso_8859-4:1988',
+                            'l4',
+                            'latin4',
+                        ],
+                        name: 'ISO-8859-4',
+                    },
+                    {
+                        labels: [
+                            'csisolatincyrillic',
+                            'cyrillic',
+                            'iso-8859-5',
+                            'iso-ir-144',
+                            'iso8859-5',
+                            'iso88595',
+                            'iso_8859-5',
+                            'iso_8859-5:1988',
+                        ],
+                        name: 'ISO-8859-5',
+                    },
+                    {
+                        labels: [
+                            'arabic',
+                            'asmo-708',
+                            'csiso88596e',
+                            'csiso88596i',
+                            'csisolatinarabic',
+                            'ecma-114',
+                            'iso-8859-6',
+                            'iso-8859-6-e',
+                            'iso-8859-6-i',
+                            'iso-ir-127',
+                            'iso8859-6',
+                            'iso88596',
+                            'iso_8859-6',
+                            'iso_8859-6:1987',
+                        ],
+                        name: 'ISO-8859-6',
+                    },
+                    {
+                        labels: [
+                            'csisolatingreek',
+                            'ecma-118',
+                            'elot_928',
+                            'greek',
+                            'greek8',
+                            'iso-8859-7',
+                            'iso-ir-126',
+                            'iso8859-7',
+                            'iso88597',
+                            'iso_8859-7',
+                            'iso_8859-7:1987',
+                            'sun_eu_greek',
+                        ],
+                        name: 'ISO-8859-7',
+                    },
+                    {
+                        labels: [
+                            'csiso88598e',
+                            'csisolatinhebrew',
+                            'hebrew',
+                            'iso-8859-8',
+                            'iso-8859-8-e',
+                            'iso-ir-138',
+                            'iso8859-8',
+                            'iso88598',
+                            'iso_8859-8',
+                            'iso_8859-8:1988',
+                            'visual',
+                        ],
+                        name: 'ISO-8859-8',
+                    },
+                    {
+                        labels: ['csiso88598i', 'iso-8859-8-i', 'logical'],
+                        name: 'ISO-8859-8-I',
+                    },
+                    {
+                        labels: [
+                            'csisolatin6',
+                            'iso-8859-10',
+                            'iso-ir-157',
+                            'iso8859-10',
+                            'iso885910',
+                            'l6',
+                            'latin6',
+                        ],
+                        name: 'ISO-8859-10',
+                    },
+                    {
+                        labels: ['iso-8859-13', 'iso8859-13', 'iso885913'],
+                        name: 'ISO-8859-13',
+                    },
+                    {
+                        labels: ['iso-8859-14', 'iso8859-14', 'iso885914'],
+                        name: 'ISO-8859-14',
+                    },
+                    {
+                        labels: [
+                            'csisolatin9',
+                            'iso-8859-15',
+                            'iso8859-15',
+                            'iso885915',
+                            'iso_8859-15',
+                            'l9',
+                        ],
+                        name: 'ISO-8859-15',
+                    },
+                    {
+                        labels: ['iso-8859-16'],
+                        name: 'ISO-8859-16',
+                    },
+                    {
+                        labels: ['cskoi8r', 'koi', 'koi8', 'koi8-r', 'koi8_r'],
+                        name: 'KOI8-R',
+                    },
+                    {
+                        labels: ['koi8-ru', 'koi8-u'],
+                        name: 'KOI8-U',
+                    },
+                    {
+                        labels: ['csmacintosh', 'mac', 'macintosh', 'x-mac-roman'],
+                        name: 'macintosh',
+                    },
+                    {
+                        labels: [
+                            'dos-874',
+                            'iso-8859-11',
+                            'iso8859-11',
+                            'iso885911',
+                            'tis-620',
+                            'windows-874',
+                        ],
+                        name: 'windows-874',
+                    },
+                    {
+                        labels: ['cp1250', 'windows-1250', 'x-cp1250'],
+                        name: 'windows-1250',
+                    },
+                    {
+                        labels: ['cp1251', 'windows-1251', 'x-cp1251'],
+                        name: 'windows-1251',
+                    },
+                    {
+                        labels: [
+                            'ansi_x3.4-1968',
+                            'ascii',
+                            'cp1252',
+                            'cp819',
+                            'csisolatin1',
+                            'ibm819',
+                            'iso-8859-1',
+                            'iso-ir-100',
+                            'iso8859-1',
+                            'iso88591',
+                            'iso_8859-1',
+                            'iso_8859-1:1987',
+                            'l1',
+                            'latin1',
+                            'us-ascii',
+                            'windows-1252',
+                            'x-cp1252',
+                        ],
+                        name: 'windows-1252',
+                    },
+                    {
+                        labels: ['cp1253', 'windows-1253', 'x-cp1253'],
+                        name: 'windows-1253',
+                    },
+                    {
+                        labels: [
+                            'cp1254',
+                            'csisolatin5',
+                            'iso-8859-9',
+                            'iso-ir-148',
+                            'iso8859-9',
+                            'iso88599',
+                            'iso_8859-9',
+                            'iso_8859-9:1989',
+                            'l5',
+                            'latin5',
+                            'windows-1254',
+                            'x-cp1254',
+                        ],
+                        name: 'windows-1254',
+                    },
+                    {
+                        labels: ['cp1255', 'windows-1255', 'x-cp1255'],
+                        name: 'windows-1255',
+                    },
+                    {
+                        labels: ['cp1256', 'windows-1256', 'x-cp1256'],
+                        name: 'windows-1256',
+                    },
+                    {
+                        labels: ['cp1257', 'windows-1257', 'x-cp1257'],
+                        name: 'windows-1257',
+                    },
+                    {
+                        labels: ['cp1258', 'windows-1258', 'x-cp1258'],
+                        name: 'windows-1258',
+                    },
+                    {
+                        labels: ['x-mac-cyrillic', 'x-mac-ukrainian'],
+                        name: 'x-mac-cyrillic',
+                    },
+                ],
+                heading: 'Legacy single-byte encodings',
+            },
+            {
+                encodings: [
+                    {
+                        labels: [
+                            'chinese',
+                            'csgb2312',
+                            'csiso58gb231280',
+                            'gb2312',
+                            'gb_2312',
+                            'gb_2312-80',
+                            'gbk',
+                            'iso-ir-58',
+                            'x-gbk',
+                        ],
+                        name: 'GBK',
+                    },
+                    {
+                        labels: ['gb18030'],
+                        name: 'gb18030',
+                    },
+                ],
+                heading: 'Legacy multi-byte Chinese (simplified) encodings',
+            },
+            {
+                encodings: [
+                    {
+                        labels: ['big5', 'big5-hkscs', 'cn-big5', 'csbig5', 'x-x-big5'],
+                        name: 'Big5',
+                    },
+                ],
+                heading: 'Legacy multi-byte Chinese (traditional) encodings',
+            },
+            {
+                encodings: [
+                    {
+                        labels: ['cseucpkdfmtjapanese', 'euc-jp', 'x-euc-jp'],
+                        name: 'EUC-JP',
+                    },
+                    {
+                        labels: ['csiso2022jp', 'iso-2022-jp'],
+                        name: 'ISO-2022-JP',
+                    },
+                    {
+                        labels: [
+                            'csshiftjis',
+                            'ms932',
+                            'ms_kanji',
+                            'shift-jis',
+                            'shift_jis',
+                            'sjis',
+                            'windows-31j',
+                            'x-sjis',
+                        ],
+                        name: 'Shift_JIS',
+                    },
+                ],
+                heading: 'Legacy multi-byte Japanese encodings',
+            },
+            {
+                encodings: [
+                    {
+                        labels: [
+                            'cseuckr',
+                            'csksc56011987',
+                            'euc-kr',
+                            'iso-ir-149',
+                            'korean',
+                            'ks_c_5601-1987',
+                            'ks_c_5601-1989',
+                            'ksc5601',
+                            'ksc_5601',
+                            'windows-949',
+                        ],
+                        name: 'EUC-KR',
+                    },
+                ],
+                heading: 'Legacy multi-byte Korean encodings',
+            },
+            {
+                encodings: [
+                    {
+                        labels: [
+                            'csiso2022kr',
+                            'hz-gb-2312',
+                            'iso-2022-cn',
+                            'iso-2022-cn-ext',
+                            'iso-2022-kr',
+                            'replacement',
+                        ],
+                        name: 'replacement',
+                    },
+                    {
+                        labels: ['unicodefffe', 'utf-16be'],
+                        name: 'UTF-16BE',
+                    },
+                    {
+                        labels: [
+                            'csunicode',
+                            'iso-10646-ucs-2',
+                            'ucs-2',
+                            'unicode',
+                            'unicodefeff',
+                            'utf-16',
+                            'utf-16le',
+                        ],
+                        name: 'UTF-16LE',
+                    },
+                    {
+                        labels: ['x-user-defined'],
+                        name: 'x-user-defined',
+                    },
+                ],
+                heading: 'Legacy miscellaneous encodings',
+            },
+        ];
+
+        const singleByteEncodings = encodingsTable.filter(group => {
+            return group.heading === 'Legacy single-byte encodings';
+        })[0].encodings;
+
+        // https://encoding.spec.whatwg.org/indexes.json
+        const singleByteIndexes = {
+            'IBM866': [
+                1040, 1041, 1042, 1043, 1044, 1045, 1046, 1047,
+                1048, 1049, 1050, 1051, 1052, 1053, 1054, 1055,
+                1056, 1057, 1058, 1059, 1060, 1061, 1062, 1063,
+                1064, 1065, 1066, 1067, 1068, 1069, 1070, 1071,
+                1072, 1073, 1074, 1075, 1076, 1077, 1078, 1079,
+                1080, 1081, 1082, 1083, 1084, 1085, 1086, 1087,
+                9617, 9618, 9619, 9474, 9508, 9569, 9570, 9558,
+                9557, 9571, 9553, 9559, 9565, 9564, 9563, 9488,
+                9492, 9524, 9516, 9500, 9472, 9532, 9566, 9567,
+                9562, 9556, 9577, 9574, 9568, 9552, 9580, 9575,
+                9576, 9572, 9573, 9561, 9560, 9554, 9555, 9579,
+                9578, 9496, 9484, 9608, 9604, 9612, 9616, 9600,
+                1088, 1089, 1090, 1091, 1092, 1093, 1094, 1095,
+                1096, 1097, 1098, 1099, 1100, 1101, 1102, 1103,
+                1025, 1105, 1028, 1108, 1031, 1111, 1038, 1118,
+                176, 8729, 183, 8730, 8470, 164, 9632, 160,
+            ],
+            'ISO-8859-2': [
+                128, 129, 130, 131, 132, 133, 134, 135,
+                136, 137, 138, 139, 140, 141, 142, 143,
+                144, 145, 146, 147, 148, 149, 150, 151,
+                152, 153, 154, 155, 156, 157, 158, 159,
+                160, 260, 728, 321, 164, 317, 346, 167,
+                168, 352, 350, 356, 377, 173, 381, 379,
+                176, 261, 731, 322, 180, 318, 347, 711,
+                184, 353, 351, 357, 378, 733, 382, 380,
+                340, 193, 194, 258, 196, 313, 262, 199,
+                268, 201, 280, 203, 282, 205, 206, 270,
+                272, 323, 327, 211, 212, 336, 214, 215,
+                344, 366, 218, 368, 220, 221, 354, 223,
+                341, 225, 226, 259, 228, 314, 263, 231,
+                269, 233, 281, 235, 283, 237, 238, 271,
+                273, 324, 328, 243, 244, 337, 246, 247,
+                345, 367, 250, 369, 252, 253, 355, 729,
+            ],
+            'ISO-8859-3': [
+                128, 129, 130, 131, 132, 133, 134, 135,
+                136, 137, 138, 139, 140, 141, 142, 143,
+                144, 145, 146, 147, 148, 149, 150, 151,
+                152, 153, 154, 155, 156, 157, 158, 159,
+                160, 294, 728, 163, 164, null, 292, 167,
+                168, 304, 350, 286, 308, 173, null, 379,
+                176, 295, 178, 179, 180, 181, 293, 183,
+                184, 305, 351, 287, 309, 189, null, 380,
+                192, 193, 194, null, 196, 266, 264, 199,
+                200, 201, 202, 203, 204, 205, 206, 207,
+                null, 209, 210, 211, 212, 288, 214, 215,
+                284, 217, 218, 219, 220, 364, 348, 223,
+                224, 225, 226, null, 228, 267, 265, 231,
+                232, 233, 234, 235, 236, 237, 238, 239,
+                null, 241, 242, 243, 244, 289, 246, 247,
+                285, 249, 250, 251, 252, 365, 349, 729,
+            ],
+            'ISO-8859-4': [
+                128, 129, 130, 131, 132, 133, 134, 135,
+                136, 137, 138, 139, 140, 141, 142, 143,
+                144, 145, 146, 147, 148, 149, 150, 151,
+                152, 153, 154, 155, 156, 157, 158, 159,
+                160, 260, 312, 342, 164, 296, 315, 167,
+                168, 352, 274, 290, 358, 173, 381, 175,
+                176, 261, 731, 343, 180, 297, 316, 711,
+                184, 353, 275, 291, 359, 330, 382, 331,
+                256, 193, 194, 195, 196, 197, 198, 302,
+                268, 201, 280, 203, 278, 205, 206, 298,
+                272, 325, 332, 310, 212, 213, 214, 215,
+                216, 370, 218, 219, 220, 360, 362, 223,
+                257, 225, 226, 227, 228, 229, 230, 303,
+                269, 233, 281, 235, 279, 237, 238, 299,
+                273, 326, 333, 311, 244, 245, 246, 247,
+                248, 371, 250, 251, 252, 361, 363, 729,
+            ],
+            'ISO-8859-5': [
+                128, 129, 130, 131, 132, 133, 134, 135,
+                136, 137, 138, 139, 140, 141, 142, 143,
+                144, 145, 146, 147, 148, 149, 150, 151,
+                152, 153, 154, 155, 156, 157, 158, 159,
+                160, 1025, 1026, 1027, 1028, 1029, 1030, 1031,
+                1032, 1033, 1034, 1035, 1036, 173, 1038, 1039,
+                1040, 1041, 1042, 1043, 1044, 1045, 1046, 1047,
+                1048, 1049, 1050, 1051, 1052, 1053, 1054, 1055,
+                1056, 1057, 1058, 1059, 1060, 1061, 1062, 1063,
+                1064, 1065, 1066, 1067, 1068, 1069, 1070, 1071,
+                1072, 1073, 1074, 1075, 1076, 1077, 1078, 1079,
+                1080, 1081, 1082, 1083, 1084, 1085, 1086, 1087,
+                1088, 1089, 1090, 1091, 1092, 1093, 1094, 1095,
+                1096, 1097, 1098, 1099, 1100, 1101, 1102, 1103,
+                8470, 1105, 1106, 1107, 1108, 1109, 1110, 1111,
+                1112, 1113, 1114, 1115, 1116, 167, 1118, 1119,
+            ],
+            'ISO-8859-6': [
+                128, 129, 130, 131, 132, 133, 134, 135,
+                136, 137, 138, 139, 140, 141, 142, 143,
+                144, 145, 146, 147, 148, 149, 150, 151,
+                152, 153, 154, 155, 156, 157, 158, 159,
+                160, null, null, null, 164, null, null, null,
+                null, null, null, null, 1548, 173, null, null,
+                null, null, null, null, null, null, null, null,
+                null, null, null, 1563, null, null, null, 1567,
+                null, 1569, 1570, 1571, 1572, 1573, 1574, 1575,
+                1576, 1577, 1578, 1579, 1580, 1581, 1582, 1583,
+                1584, 1585, 1586, 1587, 1588, 1589, 1590, 1591,
+                1592, 1593, 1594, null, null, null, null, null,
+                1600, 1601, 1602, 1603, 1604, 1605, 1606, 1607,
+                1608, 1609, 1610, 1611, 1612, 1613, 1614, 1615,
+                1616, 1617, 1618, null, null, null, null, null,
+                null, null, null, null, null, null, null, null,
+            ],
+            'ISO-8859-7': [
+                128, 129, 130, 131, 132, 133, 134, 135,
+                136, 137, 138, 139, 140, 141, 142, 143,
+                144, 145, 146, 147, 148, 149, 150, 151,
+                152, 153, 154, 155, 156, 157, 158, 159,
+                160, 8216, 8217, 163, 8364, 8367, 166, 167,
+                168, 169, 890, 171, 172, 173, null, 8213,
+                176, 177, 178, 179, 900, 901, 902, 183,
+                904, 905, 906, 187, 908, 189, 910, 911,
+                912, 913, 914, 915, 916, 917, 918, 919,
+                920, 921, 922, 923, 924, 925, 926, 927,
+                928, 929, null, 931, 932, 933, 934, 935,
+                936, 937, 938, 939, 940, 941, 942, 943,
+                944, 945, 946, 947, 948, 949, 950, 951,
+                952, 953, 954, 955, 956, 957, 958, 959,
+                960, 961, 962, 963, 964, 965, 966, 967,
+                968, 969, 970, 971, 972, 973, 974, null,
+            ],
+            'ISO-8859-8': [
+                128, 129, 130, 131, 132, 133, 134, 135,
+                136, 137, 138, 139, 140, 141, 142, 143,
+                144, 145, 146, 147, 148, 149, 150, 151,
+                152, 153, 154, 155, 156, 157, 158, 159,
+                160, null, 162, 163, 164, 165, 166, 167,
+                168, 169, 215, 171, 172, 173, 174, 175,
+                176, 177, 178, 179, 180, 181, 182, 183,
+                184, 185, 247, 187, 188, 189, 190, null,
+                null, null, null, null, null, null, null, null,
+                null, null, null, null, null, null, null, null,
+                null, null, null, null, null, null, null, null,
+                null, null, null, null, null, null, null, 8215,
+                1488, 1489, 1490, 1491, 1492, 1493, 1494, 1495,
+                1496, 1497, 1498, 1499, 1500, 1501, 1502, 1503,
+                1504, 1505, 1506, 1507, 1508, 1509, 1510, 1511,
+                1512, 1513, 1514, null, null, 8206, 8207, null,
+            ],
+            'ISO-8859-10': [
+                128, 129, 130, 131, 132, 133, 134, 135,
+                136, 137, 138, 139, 140, 141, 142, 143,
+                144, 145, 146, 147, 148, 149, 150, 151,
+                152, 153, 154, 155, 156, 157, 158, 159,
+                160, 260, 274, 290, 298, 296, 310, 167,
+                315, 272, 352, 358, 381, 173, 362, 330,
+                176, 261, 275, 291, 299, 297, 311, 183,
+                316, 273, 353, 359, 382, 8213, 363, 331,
+                256, 193, 194, 195, 196, 197, 198, 302,
+                268, 201, 280, 203, 278, 205, 206, 207,
+                208, 325, 332, 211, 212, 213, 214, 360,
+                216, 370, 218, 219, 220, 221, 222, 223,
+                257, 225, 226, 227, 228, 229, 230, 303,
+                269, 233, 281, 235, 279, 237, 238, 239,
+                240, 326, 333, 243, 244, 245, 246, 361,
+                248, 371, 250, 251, 252, 253, 254, 312,
+            ],
+            'ISO-8859-13': [
+                128, 129, 130, 131, 132, 133, 134, 135,
+                136, 137, 138, 139, 140, 141, 142, 143,
+                144, 145, 146, 147, 148, 149, 150, 151,
+                152, 153, 154, 155, 156, 157, 158, 159,
+                160, 8221, 162, 163, 164, 8222, 166, 167,
+                216, 169, 342, 171, 172, 173, 174, 198,
+                176, 177, 178, 179, 8220, 181, 182, 183,
+                248, 185, 343, 187, 188, 189, 190, 230,
+                260, 302, 256, 262, 196, 197, 280, 274,
+                268, 201, 377, 278, 290, 310, 298, 315,
+                352, 323, 325, 211, 332, 213, 214, 215,
+                370, 321, 346, 362, 220, 379, 381, 223,
+                261, 303, 257, 263, 228, 229, 281, 275,
+                269, 233, 378, 279, 291, 311, 299, 316,
+                353, 324, 326, 243, 333, 245, 246, 247,
+                371, 322, 347, 363, 252, 380, 382, 8217,
+            ],
+            'ISO-8859-14': [
+                128, 129, 130, 131, 132, 133, 134, 135,
+                136, 137, 138, 139, 140, 141, 142, 143,
+                144, 145, 146, 147, 148, 149, 150, 151,
+                152, 153, 154, 155, 156, 157, 158, 159,
+                160, 7682, 7683, 163, 266, 267, 7690, 167,
+                7808, 169, 7810, 7691, 7922, 173, 174, 376,
+                7710, 7711, 288, 289, 7744, 7745, 182, 7766,
+                7809, 7767, 7811, 7776, 7923, 7812, 7813, 7777,
+                192, 193, 194, 195, 196, 197, 198, 199,
+                200, 201, 202, 203, 204, 205, 206, 207,
+                372, 209, 210, 211, 212, 213, 214, 7786,
+                216, 217, 218, 219, 220, 221, 374, 223,
+                224, 225, 226, 227, 228, 229, 230, 231,
+                232, 233, 234, 235, 236, 237, 238, 239,
+                373, 241, 242, 243, 244, 245, 246, 7787,
+                248, 249, 250, 251, 252, 253, 375, 255,
+            ],
+            'ISO-8859-15': [
+                128, 129, 130, 131, 132, 133, 134, 135,
+                136, 137, 138, 139, 140, 141, 142, 143,
+                144, 145, 146, 147, 148, 149, 150, 151,
+                152, 153, 154, 155, 156, 157, 158, 159,
+                160, 161, 162, 163, 8364, 165, 352, 167,
+                353, 169, 170, 171, 172, 173, 174, 175,
+                176, 177, 178, 179, 381, 181, 182, 183,
+                382, 185, 186, 187, 338, 339, 376, 191,
+                192, 193, 194, 195, 196, 197, 198, 199,
+                200, 201, 202, 203, 204, 205, 206, 207,
+                208, 209, 210, 211, 212, 213, 214, 215,
+                216, 217, 218, 219, 220, 221, 222, 223,
+                224, 225, 226, 227, 228, 229, 230, 231,
+                232, 233, 234, 235, 236, 237, 238, 239,
+                240, 241, 242, 243, 244, 245, 246, 247,
+                248, 249, 250, 251, 252, 253, 254, 255,
+            ],
+            'ISO-8859-16': [
+                128, 129, 130, 131, 132, 133, 134, 135,
+                136, 137, 138, 139, 140, 141, 142, 143,
+                144, 145, 146, 147, 148, 149, 150, 151,
+                152, 153, 154, 155, 156, 157, 158, 159,
+                160, 260, 261, 321, 8364, 8222, 352, 167,
+                353, 169, 536, 171, 377, 173, 378, 379,
+                176, 177, 268, 322, 381, 8221, 182, 183,
+                382, 269, 537, 187, 338, 339, 376, 380,
+                192, 193, 194, 258, 196, 262, 198, 199,
+                200, 201, 202, 203, 204, 205, 206, 207,
+                272, 323, 210, 211, 212, 336, 214, 346,
+                368, 217, 218, 219, 220, 280, 538, 223,
+                224, 225, 226, 259, 228, 263, 230, 231,
+                232, 233, 234, 235, 236, 237, 238, 239,
+                273, 324, 242, 243, 244, 337, 246, 347,
+                369, 249, 250, 251, 252, 281, 539, 255,
+            ],
+            'KOI8-R': [
+                9472, 9474, 9484, 9488, 9492, 9496, 9500, 9508,
+                9516, 9524, 9532, 9600, 9604, 9608, 9612, 9616,
+                9617, 9618, 9619, 8992, 9632, 8729, 8730, 8776,
+                8804, 8805, 160, 8993, 176, 178, 183, 247,
+                9552, 9553, 9554, 1105, 9555, 9556, 9557, 9558,
+                9559, 9560, 9561, 9562, 9563, 9564, 9565, 9566,
+                9567, 9568, 9569, 1025, 9570, 9571, 9572, 9573,
+                9574, 9575, 9576, 9577, 9578, 9579, 9580, 169,
+                1102, 1072, 1073, 1094, 1076, 1077, 1092, 1075,
+                1093, 1080, 1081, 1082, 1083, 1084, 1085, 1086,
+                1087, 1103, 1088, 1089, 1090, 1091, 1078, 1074,
+                1100, 1099, 1079, 1096, 1101, 1097, 1095, 1098,
+                1070, 1040, 1041, 1062, 1044, 1045, 1060, 1043,
+                1061, 1048, 1049, 1050, 1051, 1052, 1053, 1054,
+                1055, 1071, 1056, 1057, 1058, 1059, 1046, 1042,
+                1068, 1067, 1047, 1064, 1069, 1065, 1063, 1066,
+            ],
+            'KOI8-U': [
+                9472, 9474, 9484, 9488, 9492, 9496, 9500, 9508,
+                9516, 9524, 9532, 9600, 9604, 9608, 9612, 9616,
+                9617, 9618, 9619, 8992, 9632, 8729, 8730, 8776,
+                8804, 8805, 160, 8993, 176, 178, 183, 247,
+                9552, 9553, 9554, 1105, 1108, 9556, 1110, 1111,
+                9559, 9560, 9561, 9562, 9563, 1169, 1118, 9566,
+                9567, 9568, 9569, 1025, 1028, 9571, 1030, 1031,
+                9574, 9575, 9576, 9577, 9578, 1168, 1038, 169,
+                1102, 1072, 1073, 1094, 1076, 1077, 1092, 1075,
+                1093, 1080, 1081, 1082, 1083, 1084, 1085, 1086,
+                1087, 1103, 1088, 1089, 1090, 1091, 1078, 1074,
+                1100, 1099, 1079, 1096, 1101, 1097, 1095, 1098,
+                1070, 1040, 1041, 1062, 1044, 1045, 1060, 1043,
+                1061, 1048, 1049, 1050, 1051, 1052, 1053, 1054,
+                1055, 1071, 1056, 1057, 1058, 1059, 1046, 1042,
+                1068, 1067, 1047, 1064, 1069, 1065, 1063, 1066,
+            ],
+            'macintosh': [
+                196, 197, 199, 201, 209, 214, 220, 225,
+                224, 226, 228, 227, 229, 231, 233, 232,
+                234, 235, 237, 236, 238, 239, 241, 243,
+                242, 244, 246, 245, 250, 249, 251, 252,
+                8224, 176, 162, 163, 167, 8226, 182, 223,
+                174, 169, 8482, 180, 168, 8800, 198, 216,
+                8734, 177, 8804, 8805, 165, 181, 8706, 8721,
+                8719, 960, 8747, 170, 186, 937, 230, 248,
+                191, 161, 172, 8730, 402, 8776, 8710, 171,
+                187, 8230, 160, 192, 195, 213, 338, 339,
+                8211, 8212, 8220, 8221, 8216, 8217, 247, 9674,
+                255, 376, 8260, 8364, 8249, 8250, 64257, 64258,
+                8225, 183, 8218, 8222, 8240, 194, 202, 193,
+                203, 200, 205, 206, 207, 204, 211, 212,
+                63743, 210, 218, 219, 217, 305, 710, 732,
+                175, 728, 729, 730, 184, 733, 731, 711,
+            ],
+            'windows-874': [
+                8364, 129, 130, 131, 132, 8230, 134, 135,
+                136, 137, 138, 139, 140, 141, 142, 143,
+                144, 8216, 8217, 8220, 8221, 8226, 8211, 8212,
+                152, 153, 154, 155, 156, 157, 158, 159,
+                160, 3585, 3586, 3587, 3588, 3589, 3590, 3591,
+                3592, 3593, 3594, 3595, 3596, 3597, 3598, 3599,
+                3600, 3601, 3602, 3603, 3604, 3605, 3606, 3607,
+                3608, 3609, 3610, 3611, 3612, 3613, 3614, 3615,
+                3616, 3617, 3618, 3619, 3620, 3621, 3622, 3623,
+                3624, 3625, 3626, 3627, 3628, 3629, 3630, 3631,
+                3632, 3633, 3634, 3635, 3636, 3637, 3638, 3639,
+                3640, 3641, 3642, null, null, null, null, 3647,
+                3648, 3649, 3650, 3651, 3652, 3653, 3654, 3655,
+                3656, 3657, 3658, 3659, 3660, 3661, 3662, 3663,
+                3664, 3665, 3666, 3667, 3668, 3669, 3670, 3671,
+                3672, 3673, 3674, 3675, null, null, null, null,
+            ],
+            'windows-1250': [
+                8364, 129, 8218, 131, 8222, 8230, 8224, 8225,
+                136, 8240, 352, 8249, 346, 356, 381, 377,
+                144, 8216, 8217, 8220, 8221, 8226, 8211, 8212,
+                152, 8482, 353, 8250, 347, 357, 382, 378,
+                160, 711, 728, 321, 164, 260, 166, 167,
+                168, 169, 350, 171, 172, 173, 174, 379,
+                176, 177, 731, 322, 180, 181, 182, 183,
+                184, 261, 351, 187, 317, 733, 318, 380,
+                340, 193, 194, 258, 196, 313, 262, 199,
+                268, 201, 280, 203, 282, 205, 206, 270,
+                272, 323, 327, 211, 212, 336, 214, 215,
+                344, 366, 218, 368, 220, 221, 354, 223,
+                341, 225, 226, 259, 228, 314, 263, 231,
+                269, 233, 281, 235, 283, 237, 238, 271,
+                273, 324, 328, 243, 244, 337, 246, 247,
+                345, 367, 250, 369, 252, 253, 355, 729,
+            ],
+            'windows-1251': [
+                1026, 1027, 8218, 1107, 8222, 8230, 8224, 8225,
+                8364, 8240, 1033, 8249, 1034, 1036, 1035, 1039,
+                1106, 8216, 8217, 8220, 8221, 8226, 8211, 8212,
+                152, 8482, 1113, 8250, 1114, 1116, 1115, 1119,
+                160, 1038, 1118, 1032, 164, 1168, 166, 167,
+                1025, 169, 1028, 171, 172, 173, 174, 1031,
+                176, 177, 1030, 1110, 1169, 181, 182, 183,
+                1105, 8470, 1108, 187, 1112, 1029, 1109, 1111,
+                1040, 1041, 1042, 1043, 1044, 1045, 1046, 1047,
+                1048, 1049, 1050, 1051, 1052, 1053, 1054, 1055,
+                1056, 1057, 1058, 1059, 1060, 1061, 1062, 1063,
+                1064, 1065, 1066, 1067, 1068, 1069, 1070, 1071,
+                1072, 1073, 1074, 1075, 1076, 1077, 1078, 1079,
+                1080, 1081, 1082, 1083, 1084, 1085, 1086, 1087,
+                1088, 1089, 1090, 1091, 1092, 1093, 1094, 1095,
+                1096, 1097, 1098, 1099, 1100, 1101, 1102, 1103,
+            ],
+            'windows-1252': [
+                8364, 129, 8218, 402, 8222, 8230, 8224, 8225,
+                710, 8240, 352, 8249, 338, 141, 381, 143,
+                144, 8216, 8217, 8220, 8221, 8226, 8211, 8212,
+                732, 8482, 353, 8250, 339, 157, 382, 376,
+                160, 161, 162, 163, 164, 165, 166, 167,
+                168, 169, 170, 171, 172, 173, 174, 175,
+                176, 177, 178, 179, 180, 181, 182, 183,
+                184, 185, 186, 187, 188, 189, 190, 191,
+                192, 193, 194, 195, 196, 197, 198, 199,
+                200, 201, 202, 203, 204, 205, 206, 207,
+                208, 209, 210, 211, 212, 213, 214, 215,
+                216, 217, 218, 219, 220, 221, 222, 223,
+                224, 225, 226, 227, 228, 229, 230, 231,
+                232, 233, 234, 235, 236, 237, 238, 239,
+                240, 241, 242, 243, 244, 245, 246, 247,
+                248, 249, 250, 251, 252, 253, 254, 255,
+            ],
+            'windows-1253': [
+                8364, 129, 8218, 402, 8222, 8230, 8224, 8225,
+                136, 8240, 138, 8249, 140, 141, 142, 143,
+                144, 8216, 8217, 8220, 8221, 8226, 8211, 8212,
+                152, 8482, 154, 8250, 156, 157, 158, 159,
+                160, 901, 902, 163, 164, 165, 166, 167,
+                168, 169, null, 171, 172, 173, 174, 8213,
+                176, 177, 178, 179, 900, 181, 182, 183,
+                904, 905, 906, 187, 908, 189, 910, 911,
+                912, 913, 914, 915, 916, 917, 918, 919,
+                920, 921, 922, 923, 924, 925, 926, 927,
+                928, 929, null, 931, 932, 933, 934, 935,
+                936, 937, 938, 939, 940, 941, 942, 943,
+                944, 945, 946, 947, 948, 949, 950, 951,
+                952, 953, 954, 955, 956, 957, 958, 959,
+                960, 961, 962, 963, 964, 965, 966, 967,
+                968, 969, 970, 971, 972, 973, 974, null,
+            ],
+            'windows-1254': [
+                8364, 129, 8218, 402, 8222, 8230, 8224, 8225,
+                710, 8240, 352, 8249, 338, 141, 142, 143,
+                144, 8216, 8217, 8220, 8221, 8226, 8211, 8212,
+                732, 8482, 353, 8250, 339, 157, 158, 376,
+                160, 161, 162, 163, 164, 165, 166, 167,
+                168, 169, 170, 171, 172, 173, 174, 175,
+                176, 177, 178, 179, 180, 181, 182, 183,
+                184, 185, 186, 187, 188, 189, 190, 191,
+                192, 193, 194, 195, 196, 197, 198, 199,
+                200, 201, 202, 203, 204, 205, 206, 207,
+                286, 209, 210, 211, 212, 213, 214, 215,
+                216, 217, 218, 219, 220, 304, 350, 223,
+                224, 225, 226, 227, 228, 229, 230, 231,
+                232, 233, 234, 235, 236, 237, 238, 239,
+                287, 241, 242, 243, 244, 245, 246, 247,
+                248, 249, 250, 251, 252, 305, 351, 255,
+            ],
+            'windows-1255': [
+                8364, 129, 8218, 402, 8222, 8230, 8224, 8225,
+                710, 8240, 138, 8249, 140, 141, 142, 143,
+                144, 8216, 8217, 8220, 8221, 8226, 8211, 8212,
+                732, 8482, 154, 8250, 156, 157, 158, 159,
+                160, 161, 162, 163, 8362, 165, 166, 167,
+                168, 169, 215, 171, 172, 173, 174, 175,
+                176, 177, 178, 179, 180, 181, 182, 183,
+                184, 185, 247, 187, 188, 189, 190, 191,
+                1456, 1457, 1458, 1459, 1460, 1461, 1462, 1463,
+                1464, 1465, 1466, 1467, 1468, 1469, 1470, 1471,
+                1472, 1473, 1474, 1475, 1520, 1521, 1522, 1523,
+                1524, null, null, null, null, null, null, null,
+                1488, 1489, 1490, 1491, 1492, 1493, 1494, 1495,
+                1496, 1497, 1498, 1499, 1500, 1501, 1502, 1503,
+                1504, 1505, 1506, 1507, 1508, 1509, 1510, 1511,
+                1512, 1513, 1514, null, null, 8206, 8207, null,
+            ],
+            'windows-1256': [
+                8364, 1662, 8218, 402, 8222, 8230, 8224, 8225,
+                710, 8240, 1657, 8249, 338, 1670, 1688, 1672,
+                1711, 8216, 8217, 8220, 8221, 8226, 8211, 8212,
+                1705, 8482, 1681, 8250, 339, 8204, 8205, 1722,
+                160, 1548, 162, 163, 164, 165, 166, 167,
+                168, 169, 1726, 171, 172, 173, 174, 175,
+                176, 177, 178, 179, 180, 181, 182, 183,
+                184, 185, 1563, 187, 188, 189, 190, 1567,
+                1729, 1569, 1570, 1571, 1572, 1573, 1574, 1575,
+                1576, 1577, 1578, 1579, 1580, 1581, 1582, 1583,
+                1584, 1585, 1586, 1587, 1588, 1589, 1590, 215,
+                1591, 1592, 1593, 1594, 1600, 1601, 1602, 1603,
+                224, 1604, 226, 1605, 1606, 1607, 1608, 231,
+                232, 233, 234, 235, 1609, 1610, 238, 239,
+                1611, 1612, 1613, 1614, 244, 1615, 1616, 247,
+                1617, 249, 1618, 251, 252, 8206, 8207, 1746,
+            ],
+            'windows-1257': [
+                8364, 129, 8218, 131, 8222, 8230, 8224, 8225,
+                136, 8240, 138, 8249, 140, 168, 711, 184, 144,
+                8216, 8217, 8220, 8221, 8226, 8211, 8212, 152,
+                8482, 154, 8250, 156, 175, 731, 159, 160,
+                null, 162, 163, 164, null, 166, 167, 216,
+                169, 342, 171, 172, 173, 174, 198, 176,
+                177, 178, 179, 180, 181, 182, 183, 248,
+                185, 343, 187, 188, 189, 190, 230, 260,
+                302, 256, 262, 196, 197, 280, 274, 268,
+                201, 377, 278, 290, 310, 298, 315, 352,
+                323, 325, 211, 332, 213, 214, 215, 370,
+                321, 346, 362, 220, 379, 381, 223, 261,
+                303, 257, 263, 228, 229, 281, 275, 269,
+                233, 378, 279, 291, 311, 299, 316, 353,
+                324, 326, 243, 333, 245, 246, 247, 371,
+                322, 347, 363, 252, 380, 382, 729,
+            ],
+            'windows-1258': [
+                8364, 129, 8218, 402, 8222, 8230, 8224, 8225,
+                710, 8240, 138, 8249, 338, 141, 142, 143,
+                144, 8216, 8217, 8220, 8221, 8226, 8211, 8212,
+                732, 8482, 154, 8250, 339, 157, 158, 376,
+                160, 161, 162, 163, 164, 165, 166, 167,
+                168, 169, 170, 171, 172, 173, 174, 175,
+                176, 177, 178, 179, 180, 181, 182, 183,
+                184, 185, 186, 187, 188, 189, 190, 191,
+                192, 193, 194, 258, 196, 197, 198, 199,
+                200, 201, 202, 203, 768, 205, 206, 207,
+                272, 209, 777, 211, 212, 416, 214, 215,
+                216, 217, 218, 219, 220, 431, 771, 223,
+                224, 225, 226, 259, 228, 229, 230, 231,
+                232, 233, 234, 235, 769, 237, 238, 239,
+                273, 241, 803, 243, 244, 417, 246, 247,
+                248, 249, 250, 251, 252, 432, 8363, 255,
+            ],
+            'x-mac-cyrillic': [
+                1040, 1041, 1042, 1043, 1044, 1045, 1046, 1047,
+                1048, 1049, 1050, 1051, 1052, 1053, 1054, 1055,
+                1056, 1057, 1058, 1059, 1060, 1061, 1062, 1063,
+                1064, 1065, 1066, 1067, 1068, 1069, 1070, 1071,
+                8224, 176, 1168, 163, 167, 8226, 182, 1030,
+                174, 169, 8482, 1026, 1106, 8800, 1027, 1107,
+                8734, 177, 8804, 8805, 1110, 181, 1169, 1032,
+                1028, 1108, 1031, 1111, 1033, 1113, 1034, 1114,
+                1112, 1029, 172, 8730, 402, 8776, 8710, 171,
+                187, 8230, 160, 1035, 1115, 1036, 1116, 1109,
+                8211, 8212, 8220, 8221, 8216, 8217, 247, 8222,
+                1038, 1118, 1039, 1119, 8470, 1025, 1105, 1103,
+                1072, 1073, 1074, 1075, 1076, 1077, 1078, 1079,
+                1080, 1081, 1082, 1083, 1084, 1085, 1086, 1087,
+                1088, 1089, 1090, 1091, 1092, 1093, 1094, 1095,
+                1096, 1097, 1098, 1099, 1100, 1101, 1102, 8364,
+            ],
+        };
+
+        function assertDecode(data, encoding) {
+            for (let i = 0, l = data.length; i < l; i++) {
+                const cp = data.charCodeAt(i);
+                let expectedCp = i < 0x80 ? i : singleByteIndexes[encoding][i - 0x80];
+                if (expectedCp === null)
+                    expectedCp = 0xfffd;
+
+                // assertEquals(cp, expectedCp, encoding + ":" + i);
+                expect(cp).toBe(expectedCp);
+            }
+        }
+        const buffer = new ArrayBuffer(255);
+        const view = new Uint8Array(buffer);
+
+        for (let i = 0, l = view.byteLength; i < l; i++)
+            view[i] = i;
+
+
+        for (let i = 0, l = singleByteEncodings.length; i < l; i++) {
+            const encoding = singleByteEncodings[i];
+            for (let i2 = 0, l2 = encoding.labels.length; i2 < l2; i2++) {
+                const label = encoding.labels[i2];
+                const decoder = new TextDecoder(label);
+
+                const data = decoder.decode(view);
+
+                expect(decoder.encoding).toBe(encoding.name.toLowerCase());
+                assertDecode(data, encoding.name);
+            }
+        }
+    });
+});
diff --git a/js.gresource.xml b/js.gresource.xml
index fc55e597..a0b37730 100644
--- a/js.gresource.xml
+++ b/js.gresource.xml
@@ -42,8 +42,10 @@
 
     <file>modules/core/_cairo.js</file>
     <file>modules/core/_common.js</file>
+    <file>modules/core/_encodings.js</file>
     <file>modules/core/_format.js</file>
     <file>modules/core/_gettext.js</file>
     <file>modules/core/_signals.js</file>
+    <file>modules/core/_text.js</file>
   </gresource>
 </gresources>
diff --git a/meson.build b/meson.build
index a828a24f..a75bca8a 100644
--- a/meson.build
+++ b/meson.build
@@ -409,6 +409,7 @@ libgjs_sources = [
     'gjs/native.cpp', 'gjs/native.h',
     'gjs/objectbox.cpp', 'gjs/objectbox.h',
     'gjs/profiler.cpp', 'gjs/profiler-private.h',
+    'gjs/textEncoding.cpp', 'gjs/textEncoding.h',
     'gjs/stack.cpp',
     'modules/console.cpp', 'modules/console.h',
     'modules/modules.cpp', 'modules/modules.h',
diff --git a/modules/core/_encodings.js b/modules/core/_encodings.js
new file mode 100644
index 00000000..93f2b99d
--- /dev/null
+++ b/modules/core/_encodings.js
@@ -0,0 +1,280 @@
+// SPDX-License-Identifier: MIT OR LGPL-2.0-or-later
+// SPDX-FileCopyrightText: Node.js contributors. All rights reserved.
+
+// Modified from https://github.com/nodejs/node/blob/master/lib/internal/encoding.js
+// Data originally from https://encoding.spec.whatwg.org/encodings.json
+
+/* exported getEncodingFromLabel */
+
+const encodings = new Map([
+    ['unicode-1-1-utf-8', 'utf-8'],
+    ['utf8', 'utf-8'],
+    ['utf-8', 'utf-8'],
+    ['866', 'ibm866'],
+    ['cp866', 'ibm866'],
+    ['csibm866', 'ibm866'],
+    ['ibm866', 'ibm866'],
+    ['csisolatin2', 'iso-8859-2'],
+    ['iso-8859-2', 'iso-8859-2'],
+    ['iso-ir-101', 'iso-8859-2'],
+    ['iso8859-2', 'iso-8859-2'],
+    ['iso88592', 'iso-8859-2'],
+    ['iso_8859-2', 'iso-8859-2'],
+    ['iso_8859-2:1987', 'iso-8859-2'],
+    ['l2', 'iso-8859-2'],
+    ['latin2', 'iso-8859-2'],
+    ['csisolatin3', 'iso-8859-3'],
+    ['iso-8859-3', 'iso-8859-3'],
+    ['iso-ir-109', 'iso-8859-3'],
+    ['iso8859-3', 'iso-8859-3'],
+    ['iso88593', 'iso-8859-3'],
+    ['iso_8859-3', 'iso-8859-3'],
+    ['iso_8859-3:1988', 'iso-8859-3'],
+    ['l3', 'iso-8859-3'],
+    ['latin3', 'iso-8859-3'],
+    ['csisolatin4', 'iso-8859-4'],
+    ['iso-8859-4', 'iso-8859-4'],
+    ['iso-ir-110', 'iso-8859-4'],
+    ['iso8859-4', 'iso-8859-4'],
+    ['iso88594', 'iso-8859-4'],
+    ['iso_8859-4', 'iso-8859-4'],
+    ['iso_8859-4:1988', 'iso-8859-4'],
+    ['l4', 'iso-8859-4'],
+    ['latin4', 'iso-8859-4'],
+    ['csisolatincyrillic', 'iso-8859-5'],
+    ['cyrillic', 'iso-8859-5'],
+    ['iso-8859-5', 'iso-8859-5'],
+    ['iso-ir-144', 'iso-8859-5'],
+    ['iso8859-5', 'iso-8859-5'],
+    ['iso88595', 'iso-8859-5'],
+    ['iso_8859-5', 'iso-8859-5'],
+    ['iso_8859-5:1988', 'iso-8859-5'],
+    ['arabic', 'iso-8859-6'],
+    ['asmo-708', 'iso-8859-6'],
+    ['csiso88596e', 'iso-8859-6'],
+    ['csiso88596i', 'iso-8859-6'],
+    ['csisolatinarabic', 'iso-8859-6'],
+    ['ecma-114', 'iso-8859-6'],
+    ['iso-8859-6', 'iso-8859-6'],
+    ['iso-8859-6-e', 'iso-8859-6'],
+    ['iso-8859-6-i', 'iso-8859-6'],
+    ['iso-ir-127', 'iso-8859-6'],
+    ['iso8859-6', 'iso-8859-6'],
+    ['iso88596', 'iso-8859-6'],
+    ['iso_8859-6', 'iso-8859-6'],
+    ['iso_8859-6:1987', 'iso-8859-6'],
+    ['csisolatingreek', 'iso-8859-7'],
+    ['ecma-118', 'iso-8859-7'],
+    ['elot_928', 'iso-8859-7'],
+    ['greek', 'iso-8859-7'],
+    ['greek8', 'iso-8859-7'],
+    ['iso-8859-7', 'iso-8859-7'],
+    ['iso-ir-126', 'iso-8859-7'],
+    ['iso8859-7', 'iso-8859-7'],
+    ['iso88597', 'iso-8859-7'],
+    ['iso_8859-7', 'iso-8859-7'],
+    ['iso_8859-7:1987', 'iso-8859-7'],
+    ['sun_eu_greek', 'iso-8859-7'],
+    ['csiso88598e', 'iso-8859-8'],
+    ['csisolatinhebrew', 'iso-8859-8'],
+    ['hebrew', 'iso-8859-8'],
+    ['iso-8859-8', 'iso-8859-8'],
+    ['iso-8859-8-e', 'iso-8859-8'],
+    ['iso-ir-138', 'iso-8859-8'],
+    ['iso8859-8', 'iso-8859-8'],
+    ['iso88598', 'iso-8859-8'],
+    ['iso_8859-8', 'iso-8859-8'],
+    ['iso_8859-8:1988', 'iso-8859-8'],
+    ['visual', 'iso-8859-8'],
+    ['csiso88598i', 'iso-8859-8-i'],
+    ['iso-8859-8-i', 'iso-8859-8-i'],
+    ['logical', 'iso-8859-8-i'],
+    ['csisolatin6', 'iso-8859-10'],
+    ['iso-8859-10', 'iso-8859-10'],
+    ['iso-ir-157', 'iso-8859-10'],
+    ['iso8859-10', 'iso-8859-10'],
+    ['iso885910', 'iso-8859-10'],
+    ['l6', 'iso-8859-10'],
+    ['latin6', 'iso-8859-10'],
+    ['iso-8859-13', 'iso-8859-13'],
+    ['iso8859-13', 'iso-8859-13'],
+    ['iso885913', 'iso-8859-13'],
+    ['iso-8859-14', 'iso-8859-14'],
+    ['iso8859-14', 'iso-8859-14'],
+    ['iso885914', 'iso-8859-14'],
+    ['csisolatin9', 'iso-8859-15'],
+    ['iso-8859-15', 'iso-8859-15'],
+    ['iso8859-15', 'iso-8859-15'],
+    ['iso885915', 'iso-8859-15'],
+    ['iso_8859-15', 'iso-8859-15'],
+    ['iso-8859-16', 'iso-8859-16'],
+    ['ISO-8859-16', 'iso-8859-16'],
+    ['l9', 'iso-8859-15'],
+    ['cskoi8r', 'koi8-r'],
+    ['koi', 'koi8-r'],
+    ['koi8', 'koi8-r'],
+    ['koi8-r', 'koi8-r'],
+    ['koi8_r', 'koi8-r'],
+    ['koi8-ru', 'koi8-u'],
+    ['koi8-u', 'koi8-u'],
+    ['csmacintosh', 'macintosh'],
+    ['mac', 'macintosh'],
+    ['macintosh', 'macintosh'],
+    ['x-mac-roman', 'macintosh'],
+    ['dos-874', 'windows-874'],
+    ['iso-8859-11', 'windows-874'],
+    ['iso8859-11', 'windows-874'],
+    ['iso885911', 'windows-874'],
+    ['tis-620', 'windows-874'],
+    ['windows-874', 'windows-874'],
+    ['cp1250', 'windows-1250'],
+    ['windows-1250', 'windows-1250'],
+    ['x-cp1250', 'windows-1250'],
+    ['cp1251', 'windows-1251'],
+    ['windows-1251', 'windows-1251'],
+    ['x-cp1251', 'windows-1251'],
+    ['ansi_x3.4-1968', 'windows-1252'],
+    ['ascii', 'windows-1252'],
+    ['cp1252', 'windows-1252'],
+    ['cp819', 'windows-1252'],
+    ['csisolatin1', 'windows-1252'],
+    ['ibm819', 'windows-1252'],
+    ['iso-8859-1', 'windows-1252'],
+    ['iso-ir-100', 'windows-1252'],
+    ['iso8859-1', 'windows-1252'],
+    ['iso88591', 'windows-1252'],
+    ['iso_8859-1', 'windows-1252'],
+    ['iso_8859-1:1987', 'windows-1252'],
+    ['l1', 'windows-1252'],
+    ['latin1', 'windows-1252'],
+    ['us-ascii', 'windows-1252'],
+    ['windows-1252', 'windows-1252'],
+    ['x-cp1252', 'windows-1252'],
+    ['cp1253', 'windows-1253'],
+    ['windows-1253', 'windows-1253'],
+    ['x-cp1253', 'windows-1253'],
+    ['cp1254', 'windows-1254'],
+    ['csisolatin5', 'windows-1254'],
+    ['iso-8859-9', 'windows-1254'],
+    ['iso-ir-148', 'windows-1254'],
+    ['iso8859-9', 'windows-1254'],
+    ['iso88599', 'windows-1254'],
+    ['iso_8859-9', 'windows-1254'],
+    ['iso_8859-9:1989', 'windows-1254'],
+    ['l5', 'windows-1254'],
+    ['latin5', 'windows-1254'],
+    ['windows-1254', 'windows-1254'],
+    ['x-cp1254', 'windows-1254'],
+    ['cp1255', 'windows-1255'],
+    ['windows-1255', 'windows-1255'],
+    ['x-cp1255', 'windows-1255'],
+    ['cp1256', 'windows-1256'],
+    ['windows-1256', 'windows-1256'],
+    ['x-cp1256', 'windows-1256'],
+    ['cp1257', 'windows-1257'],
+    ['windows-1257', 'windows-1257'],
+    ['x-cp1257', 'windows-1257'],
+    ['cp1258', 'windows-1258'],
+    ['windows-1258', 'windows-1258'],
+    ['x-cp1258', 'windows-1258'],
+    ['x-mac-cyrillic', 'x-mac-cyrillic'],
+    ['x-mac-ukrainian', 'x-mac-cyrillic'],
+    ['chinese', 'gbk'],
+    ['csgb2312', 'gbk'],
+    ['csiso58gb231280', 'gbk'],
+    ['gb2312', 'gbk'],
+    ['gb_2312', 'gbk'],
+    ['gb_2312-80', 'gbk'],
+    ['gbk', 'gbk'],
+    ['iso-ir-58', 'gbk'],
+    ['x-gbk', 'gbk'],
+    ['gb18030', 'gb18030'],
+    ['big5', 'big5'],
+    ['big5-hkscs', 'big5'],
+    ['cn-big5', 'big5'],
+    ['csbig5', 'big5'],
+    ['x-x-big5', 'big5'],
+    ['cseucpkdfmtjapanese', 'euc-jp'],
+    ['euc-jp', 'euc-jp'],
+    ['x-euc-jp', 'euc-jp'],
+    ['csiso2022jp', 'iso-2022-jp'],
+    ['iso-2022-jp', 'iso-2022-jp'],
+    ['csshiftjis', 'shift_jis'],
+    ['ms932', 'shift_jis'],
+    ['ms_kanji', 'shift_jis'],
+    ['shift-jis', 'shift_jis'],
+    ['shift_jis', 'shift_jis'],
+    ['sjis', 'shift_jis'],
+    ['windows-31j', 'shift_jis'],
+    ['x-sjis', 'shift_jis'],
+    ['cseuckr', 'euc-kr'],
+    ['csksc56011987', 'euc-kr'],
+    ['euc-kr', 'euc-kr'],
+    ['iso-ir-149', 'euc-kr'],
+    ['korean', 'euc-kr'],
+    ['ks_c_5601-1987', 'euc-kr'],
+    ['ks_c_5601-1989', 'euc-kr'],
+    ['ksc5601', 'euc-kr'],
+    ['ksc_5601', 'euc-kr'],
+    ['windows-949', 'euc-kr'],
+    ['utf-16be', 'utf-16be'],
+    ['utf-16le', 'utf-16le'],
+    ['utf-16', 'utf-16le'],
+]);
+
+// Some of the web-specified encodings use
+// aliases which aren't supported in iconv
+const internalEncodings = new Map([
+    ['x-mac-cyrillic', 'MacCyrillic'],
+    // For our purposes we can encoding 8-i as 8
+    ['iso-8859-8-i', 'iso-8859-8'],
+]);
+
+/**
+ * Trims ASCII whitespace from a string.
+ * `String.prototype.trim` removes non-ASCII whitespace.
+ *
+ * @param {string} label the label to trim
+ * @returns {string}
+ */
+const trimAsciiWhitespace = label => {
+    let s = 0;
+    let e = label.length;
+    while (s < e && (
+        label[s] === '\u0009' ||
+        label[s] === '\u000a' ||
+        label[s] === '\u000c' ||
+        label[s] === '\u000d' ||
+        label[s] === '\u0020'))
+        s++;
+
+    while (e > s && (
+        label[e - 1] === '\u0009' ||
+        label[e - 1] === '\u000a' ||
+        label[e - 1] === '\u000c' ||
+        label[e - 1] === '\u000d' ||
+        label[e - 1] === '\u0020'))
+        e--;
+
+    return label.slice(s, e);
+};
+
+/**
+ * @param {string} label the encoding label
+ * @returns {string | undefined}
+ */
+function getEncodingFromLabel(label) {
+    const enc = encodings.get(label);
+
+    if (enc !== undefined) {
+        return {
+            internal: internalEncodings.get(enc),
+            external: enc,
+        };
+    }
+
+
+    const trimmed = encodings.get(trimAsciiWhitespace(label.toLowerCase()));
+
+    return {internal: internalEncodings.get(trimmed), external: trimmed};
+}
diff --git a/modules/core/_text.js b/modules/core/_text.js
new file mode 100644
index 00000000..9bdc7ef2
--- /dev/null
+++ b/modules/core/_text.js
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: MIT OR LGPL-2.0-or-later
+// SPDX-FileCopyrightText: Evan Welsh
+
+const Encoding = imports._encodingNative;
+
+const { getEncodingFromLabel } = imports._encodings;
+
+var TextDecoder = class TextDecoder {
+    /**  
+     * @type {string}
+     */
+    encoding;
+
+    /**  
+     * @type {boolean}
+     */
+    ignoreBOM;
+
+    /**  
+     * @type {boolean}
+     */
+    fatal;
+
+    get [Symbol.toStringTag]() {
+        return 'TextDecoder';
+    }
+
+    /**
+     * @param {string} encoding 
+     * @param {object} [options]
+     * @param {boolean=} options.fatal
+     * @param {boolean=} options.ignoreBOM 
+     */
+    constructor(encoding = 'utf-8', options = {}) {
+        const { fatal = false, ignoreBOM = false } = options;
+
+        const encodings = getEncodingFromLabel(encoding);
+        const enc = encodings.internal ?? encodings.external;
+
+        if (enc === undefined) {
+            throw new Error(`Invalid encoding label: '${encoding}'`);
+        }
+
+        Object.defineProperty(this, '_internalEncoding', {
+            value: enc,
+            enumerable: true,
+            writable: false,
+            configurable: false,
+        });
+
+        Object.defineProperty(this, 'encoding', {
+            value: encodings.external,
+            enumerable: true,
+            writable: false,
+            configurable: false,
+        });
+
+        Object.defineProperty(this, 'ignoreBOM', {
+            value: ignoreBOM,
+            enumerable: true,
+            writable: false,
+            configurable: false,
+        });
+
+        Object.defineProperty(this, 'fatal', {
+            value: fatal,
+            enumerable: true,
+            writable: false,
+            configurable: false,
+        });
+    }
+
+    decode(bytes, options = {}) {
+        const { stream = false } = options;
+
+        if (stream) {
+            throw new Error(`TextDecoder does not implement the 'stream' option.`);
+        }
+
+        /** @type {Uint8Array} */
+        let input;
+
+        if (bytes instanceof ArrayBuffer) {
+            input = new Uint8Array(bytes);
+        } else if (bytes instanceof Uint8Array) {
+            input = bytes;
+        } else if (bytes instanceof Object.getPrototypeOf(Uint8Array)) {
+            let { buffer, byteLength, byteOffset } = /** @type {Uint32Array} */ (bytes);
+            input = new Uint8Array(buffer, byteOffset, byteLength);
+        } else if (bytes === undefined) {
+            input = new Uint8Array(0);
+        } else {
+            throw new Error(`Provided input cannot be converted to ArrayBufferView or ArrayBuffer`);
+        }
+        
+        if (this.ignoreBOM && input.length > 2 && input[0] === 0xEF && input[1] === 0xBB && input[2] === 
0xBF) {
+            if (this.encoding !== 'utf-8') {
+                throw new Error(`Cannot ignore BOM for non-UTF8 encoding.`);
+            }
+            
+            let { buffer, byteLength, byteOffset } = input;
+            input = new Uint8Array(buffer, byteOffset + 3, byteLength - 3);
+        }
+
+        return Encoding.decode(input, this.fatal, this._internalEncoding);
+    }
+}
+
+var TextEncoder = class TextEncoder {
+    get [Symbol.toStringTag]() {
+        return 'TextEncoder';
+    }
+
+    get encoding() {
+        return 'utf-8';
+    }
+
+    encode(input = '') {
+        // The TextEncoder specification only allows for UTF-8 encoding.
+        return Encoding.encode(`${input}`, 'UTF-8');
+    }
+
+    encodeInto(input = '', output = new Uint8Array()) {
+        // The TextEncoder specification only allows for UTF-8 encoding.
+        return Encoding.encodeInto(`${input}`, output);
+    }
+}
\ No newline at end of file
diff --git a/modules/core/overrides/GLib.js b/modules/core/overrides/GLib.js
index 5e3800a9..16061abd 100644
--- a/modules/core/overrides/GLib.js
+++ b/modules/core/overrides/GLib.js
@@ -51,10 +51,7 @@ function _readSingleType(signature, forceSimple) {
 }
 
 function _makeBytes(byteArray) {
-    if (byteArray instanceof Uint8Array || byteArray instanceof ByteArray.ByteArray)
-        return ByteArray.toGBytes(byteArray);
-    else
-        return new GLib.Bytes(byteArray);
+    return new GLib.Bytes(byteArray);
 }
 
 function _packVariant(signature, value) {
diff --git a/modules/script/_bootstrap/default.js b/modules/script/_bootstrap/default.js
index e31d80cb..1ac83ac5 100644
--- a/modules/script/_bootstrap/default.js
+++ b/modules/script/_bootstrap/default.js
@@ -6,8 +6,21 @@
     'use strict';
 
     const {print, printerr, log, logError} = imports._print;
+    const {TextEncoder, TextDecoder} = imports._text;
 
     Object.defineProperties(exports, {
+        TextEncoder: {
+            configurable: false,
+            enumerable: true,
+            writable: false,
+            value: TextEncoder,
+        },
+        TextDecoder: {
+            configurable: false,
+            enumerable: true,
+            writable: false,
+            value: TextDecoder,
+        },
         print: {
             configurable: false,
             enumerable: true,
diff --git a/modules/script/byteArray.js b/modules/script/byteArray.js
index fad022d2..9fe9a0e3 100644
--- a/modules/script/byteArray.js
+++ b/modules/script/byteArray.js
@@ -2,15 +2,61 @@
 // SPDX-License-Identifier: MIT OR LGPL-2.0-or-later
 // SPDX-FileCopyrightText: 2017 Philip Chimento <philip chimento gmail com>
 
+const Encoding = imports._encodingNative;
+
 /* eslint no-redeclare: ["error", { "builtinGlobals": false }] */  // for toString
-var {fromGBytes, fromString, toGBytes, toString} = imports._byteArrayNative;
+var {fromGBytes, defineToString} = imports._byteArrayNative;
+
+const {GLib} = imports.gi;
 
 // For backwards compatibility
 
+/**
+ * @param {Iterable<number>} a
+ * @returns {ByteArray}
+ */
 function fromArray(a) {
     return new ByteArray(Uint8Array.from(a));
 }
 
+/**
+ * @param {Uint8Array} array
+ * @returns {GLib.Bytes}
+ */
+function toGBytes(array) {
+    if (!(array instanceof Uint8Array))
+        throw new Error('Argument to ByteArray.toGBytes() must be a Uint8Array');
+
+
+    return new GLib.Bytes(array);
+}
+
+/**
+ * @param {Uint8Array} array
+ * @param {string} [encoding]
+ * @returns {string}
+ */
+function toString(array, encoding = 'utf-8') {
+    if (!(array instanceof Uint8Array))
+        throw new Error('Argument to ByteArray.toString() must be a Uint8Array');
+
+
+    return Encoding.decode(array, true, encoding);
+}
+
+/**
+ * @param {string} str
+ * @param {string} [encoding]
+ * @returns {Uint8Array}
+ */
+function fromString(str, encoding = 'utf-8') {
+    const array = Encoding.encode(str, encoding);
+
+    defineToString(array);
+
+    return array;
+}
+
 var ByteArray = class ByteArray {
     constructor(arg = 0) {
         if (arg instanceof Uint8Array)


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