使用内容脚本定义全局变量

Question

I am creating a Firefox extension, and one feature of it that I would like is the ability for the user to inject a script or stylesheet into a specific website, rather like Greasemonkey (except that this will only be for one site). I am adding some functions for the scripts to make use of, which I intended to add from the Content Script into the main (unsafe) window. On the MDN blog , it says that they have made changes to how it should be implemented, so I have based my code on the new implementation as advised in the post, so this is what I have:

var $jq = jQuery.noConflict();//Yes, I am also injecting jQuery at the same time
console.log("created jquery object"); //This works
exportFunction($jq, unsafeWindow, {defineAs: "$jq"});
console.log("This will never be called");

But execution of the script just stops, and in the console it prints Message: TypeError: window is null . I am testing in Firefox 28 predominantly (I can't seem to get Firefox for Ubuntu to update beyond that right now, and a whole load of issues are forcing me to use Ubuntu in a VM for this), but in Nightly 31a1 (Win7) nothing is ever injected, including a hardcoded style (that works on FF28) so I will have to figure that out at some point. (The PageMod code is here:

var lttWorker = sdk.pageMod.PageMod({
    include:["*"],
    /*contentScriptFile: [sdk.data.url("jquery.large.js"), sdk.data.url("scripts/bootstrapper.js")],
    contentScriptWhen: "ready",*/ //This is commented to test whether it was an issue with the script. It's not.
    contentStyle: "#header_bar{background-color:green;}", //This is injected in FF28 but not 31
    attachTo: ["existing", "top"],
    onAttach: function(){desktopNotifications({title:"attached content worker", text:"The content worker has been successfully attached"})} //This is called in FF28 but not 31
});
lttWorker.on("error", function(){callError("pageWorker failed");}); //This never gets called. Ever.

if anybody is interested)

EDIT: I have now tried it on Firefox 30b and there are still a load of issues, although they seem to be slightly different to both FF28 and 31...

Answer 1

First of all: These new functions are supported in Firefox 30 and later. See @canuckistani answer.

The exportFunction API is way too limited to actually inject something like jQuery with all the complex objects being or containing DOM nodes. That simply won't fly with the structured-clone algorithm that is applied to arguments. The API is meant as a way for add-ons to communicate with pages bi-directionally, and not to inject complex libraries.

Your best bet is actually creating a script tag using the DOM APIs and putting jQuery there.