Using a Greasemonkey script to add javascript, from other sites, to a page

Question

Is it possible to use a Greasemonkey script to add in JS scripts from other sites to a page, so that they run?

Answer 1

You can simply create a script element and add it to the document

// ==UserScript==
// @name       My Fancy New Userscript
// @description  enter something useful
// @match      http://*/*
// ==/UserScript==

(function () {
    var scriptElement = document.createElement( "script" );
    scriptElement.type = "text/javascript";
    scriptElement.src = "url to your script";
    document.body.appendChild( scriptElement );
})();

If you simply want the script to run then this is enough. If its a library like jQuery you want to use in your userscript it gets tricky. There are 2 ways that I'm aware of:

• One is to use the require tag of greasemonkey.
• The other one requires the same creation of a script element like shown above but you need to wait for it to load so scriptElement.onload = function () {} is needed and you'd have to use unsafeWindow to access variables from your library then.

I recommend the first method if this is a pure greasemonkey script because only than you script is encapsulated from the site.