Question

I am developing a Firefox addon. What I want to do is to inject a custom JavaScript function.

i.e.

function foo() {..}

So all the pages can call the foo without define it first.

I have look from other answer such as: http://groups.google.com/group/greasemonkey-users/browse_thread/thread/3d82a2e7322c3fce

But it requires modification on the web page. What if perhaps I want to inject the function foo into Google.com? Is it possible to do so?

I can do it with a userscript, but I want to use the extension approach if possible.

Answer 1

What if you make a simple href with javascript function on the page.
Like bookmarklets work.

Here is a sample code :

function(scriptUrl) {

    var newScript = document.createElement('script');

    // the Math.random() part is for avoiding the cache
    newScript.src = scriptUrl + '?dummy=' + Math.random();

    // append the new script to the dom
    document.body.appendChild(newScript);

    // execute your newly available function
    window.foo();

}('[url of your online script]')

To use it, put your script’s url.
It must be only one line of code, url formated, but for code readability I’ve formated it.

I’ve never developed a Firefox extension, but for javascript injection that’s how I would roll.

Hope it helped.