Get Firefox to run XUL type script on startup

Question

With Firefox 17.0.1 I am using an add-on called KeyConfig 20110522 to set some new hot keys and also set the acceltext of menuitems for my new keys as well as for add-ons that do not bother to do so.

I want the acceltext of the menuitems to be set when Firefox starts , but currently I am just using a hot key to execute the following code against the UI via KeyConfig :

document.getElementById("tabmix-menu")
  .setAttribute("acceltext","Alt+Ctrl+Shift+T");
// more of the same...

I need a couple of beginners tips:

• How can I execute arbitrary code against the UI in the same way as I execute against an HTML page via the console?

• Is there a sneaky way to get a clump of code to execute on browser start-up without delving into XUL development?

• Is there a way to trace commands executed against the UI so I can get at command calls instead of using triggers when I set my hot keys like so:

document.getElementById("tabmix-menu").click();

Any other tips on this type of low-level hacking would also be welcome.

Answer 1

You can execute arbitrary code against the Firefox UI from an addon, but as you say, doing all the XUL related stuff is a bit boring :-)

Enter "Bootstrapped" extensions!

A "Bootstrapped" (or re-startless) extension needs only an install.rdf file to identify the addon, and a bootstrap.js file to implement the bootstrap interface.

• Bootstrapped Extension: https://developer.mozilla.org/en-US/docs/Extensions/Bootstrapped_extensions

• Good example: http://blog.fpmurphy.com/2011/02/firefox-4-restartless-add-ons.html

The bootstrap interface can be implemented very simply:

function install() {}
function uninstall() {}
function shutdown(data, reason) {}
function startup(data, reason) { /* YOUR ARBITRARY CODE HERE! */ }

You compile the extension by putting install.rdf and bootstrap.js into the top-level of a new zip file, and rename the zip file extension to .xpi.

Your code is privileged and can use any of the Mozilla platform APIs. There is however an issue of timing. The moment-in-time at which the "startup" function is executed is one at which no Chrome window objects exist yet!

If it's important for your code that you have a Chrome Window, we need to wait for it to appear:

// useful services.
Cu.import("resource://gre/modules/Services.jsm");    
var loader = Cc["@mozilla.org/moz/jssubscript-loader;1"]
                .getService(Ci.mozIJSSubScriptLoader);

var wmSvc = Cc["@mozilla.org/appshell/window-mediator;1"]
                .getService(Ci.nsIWindowMediator);

var logSvc = Cc["@mozilla.org/consoleservice;1"]
                .getService(Ci.nsIConsoleService);

// get the first gBrowser 
var done_startup = 0;
var windowListener;
function do_startup(win) {

    if (done_startup) return;
    done_startup = 1;
    wmSvc.removeListener(windowListener);

    var browserEnum = wmSvc.getEnumerator("navigator:browser");
    var browserWin = browserEnum.getNext();
    var tabbrowser = browserWin.gBrowser;

    /* your code goes here! */
}

// window listener implementation
windowListener = {
    onWindowTitleChange: function(aWindow, aTitle) {},
    onCloseWindow:       function(aWindow) {},
    onOpenWindow:        function(aWindow) {
        var win = aWindow.QueryInterface(Ci.nsIInterfaceRequestor)
                     .getInterface(Ci.nsIDOMWindowInternal || Ci.nsIDOMWindow);
        win.addEventListener("load", function(aEvent) {
            win.removeEventListener("load", arguments.callee, false);
            if (aEvent.originalTarget.nodeName != "#document") return;
            do_startup();
        }
};

// CODE ENTRY POINT (put this in bootstrap "startup" function)
wmSvc.addListener(windowListener);