Firefox extension: Refer to object defined in bootstrap.js from XUL file - firefox

Question

I'm trying to contribute to a Firefox extension I use, but I have no idea what I'm doing :)
I've got a dialog powered by a XUL document to gather some data from the user. That's all fine and good. But when the user confirms the dialog, I need to call a function defined on an object that's defined in my bootstrap.js file. Is that possible to do directly? e.g., in the XUL file:
<prefpanes id="my-pane" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
<script>
function myCallback() {
PassFF.myAction(); // PassFF is undefined here
};
</script>
<prefpane>
<button id="my-button" oncommand="myCallback();" />
</prefpane>
</prefpanes>
If that's not possible, is it possible to register a callback when I open the document in the first place? Something like this:
var dialog = window.openDialog("chrome://passff/content/mypane.xul",
"my_pane_name",
"chrome,titlebar,toolbar,modal");
dialog.addEventListener('close', function(event) {
PassFF.myAction(); // PassFF is defined here, but the event doesn't fire
});
I've tried things like importing the bootstrap.js script in my XUL document with another script tag, adding another "content" line to the manifest to expose the file, different events (unload, command, click) but couldn't figure out any of these approaches either.
Any tips?

Answer 1

You can use, for example, platform observer mechanics.
this is "signals.js" file (module):
let EXPORTED_SYMBOLS = ["addSignalListener", "removeSignalListener", "emitSignal", "signalNamePrefix"];
const {utils:Cu, classes:Cc, interfaces:Ci, results:Cr} = Components;
function genUUID () {
let uuidgen = Cc["#mozilla.org/uuid-generator;1"].createInstance(Ci.nsIUUIDGenerator);
if (!uuidgen) throw new Error("no UUID generator available!");
return uuidgen.generateUUID().toString().replace(/[^-a-z0-9]/ig, "");
}
const signalNamePrefix = "signal-"+genUUID()+"-";
const obs = Cc["#mozilla.org/observer-service;1"].getService(Ci.nsIObserverService);
let observers = {};
function addSignalListener (name, cback) {
if (typeof(name) !== "string" || !name) throw new Error("invalid signal name");
if (typeof(cback) !== "function") throw new Error("callback function expected");
// check if already here
if (cback in observers) {
let names = observers[cback];
if (name in names) return; // nothing to do
} else {
observers[cback] = {};
}
let observer = {
observe: function (subject, topic, data) {
topic = topic.substr(signalNamePrefix.length); // remove prefix
if (data && data.length) {
try {
data = JSON.parse(data);
} catch (e) {
Cu.reportError(e);
return;
}
} else {
data = null;
}
cback(topic, data);
},
};
obs.addObserver(observer, signalNamePrefix+name, false);
observers[cback][name] = observer;
}
function removeSignalListener (name, cback) {
if (typeof(name) !== "string" || !name) throw new Error("invalid signal name");
if (typeof(cback) !== "function") throw new Error("callback function expected");
// find observer
let names = observers[cback];
if (names === undefined) return; // nothing to do
if (!(name in names)) return; // nothing to do
try { obs.removeObserver(observers[cback][name], name); } catch (e) {}
}
function emitSignal (name, data) {
if (typeof(name) !== "string" || !name) throw new Error("invalid signal name");
data = (typeof(data) === "undefined" ? null : (data !== null ? JSON.stringify(data) : null));
obs.notifyObservers(null, signalNamePrefix+name, data);
}
sample use:
Components.utils.import("chrome://myext/content/signals.js");
dump(signalNamePrefix+"\n");
addSignalListener("mysignal", function (signame, data) {
dump("MYSIGNAL("+signame+"): "+data+"\n");
for (let [k, v] of Iterator(data)) dump(" ["+k+"]=["+v+"]\n");
});
emitSignal("mysignal", {any:42, data:[669], here:"wow!"});
here just import "signals.js" in your "bootstrap.js", and add signal listener. then import "signals.js" in your dialog js, and emit signal with the data you need.