GJS: How to communicate with js inside webkit webview

[Rich <rl6 shinyblue net>]

Hi

I have a webkit webview, set up as in the hello tutorial[1]. I'd like to 
be able to access JS inside the webview (or vice versa). e.g. I want my 
GJS to allow the user to select a directory, and then to pass the 
filenames into the web app.

From what I've read, I tried this

        this._webView.connect('window-object-cleared', Lang.bind(this, 
this.my_test));

And the docs[2] suggest that this signal should come with the window 
object and the context for the JS environment inside the webview. So I 
thought I could just add to this and thereby communicate with something 
inside.

But my method my_test does not seem to be receiving all the parameters 
it should.

e.g.

    my_test:function(wv,f,c,w,u){  //web_view, frame, context, 
window_object, user_data) {
        c.test123 = 123;
    },

gives me
    JS ERROR: !!!   Exception was: TypeError: c is undefined
    JS ERROR: !!!     lineNumber = '30'
    JS ERROR: !!!     fileName = '"hello.js"'
    JS ERROR: !!!     stack = '"([object 
_private_WebKit_WebView],[object _private_WebKit_WebFr
ame],(void 0),(void 0))@hello.js:30
wrapper([object _private_WebKit_WebView],[object 
_private_WebKit_WebFrame],(void 0),(void 0))@/
usr/share/gjs-1.0/lang.js:204
@hello.js:64

I'm a complete beginner to GJS and am finding it v difficult. I can't 
find a way, either, to debug the thing. Even if I could write to stdout 
that would help. Is Looking Glass just for extensions? Any tips most 
welcome!

Thanks
Rich



[1]: 
https://developer.gnome.org/gnome-devel-demos/unstable/hellognome.js.html.en
[2]: 
http://webkitgtk.org/reference/webkitgtk/stable/webkitgtk-webkitwebview.html#WebKitWebView-window-object-cleared