Greasemonkey guide for Experienced Javascript Developers?

Question

I really really want to write a GreaseMonkey extension.

I have written a lot of javascript in my life.

I am looking for a guide that will tell me quickly, what exactly the GreaseMonkey environment is and does, from the perspective of someone who is familiar with everything going on in browser based Javascript.

I.e. no platitudes about how best to do things, or what has been done in the past, just a plain and simple, "this is what is going to happen to your code. " "This is the environment it will be executed in."

And I can't find one....

Answer 1

Dive into Greasemonkey is probably the best reference.

Also, Greasemonkey official docs may be helpful.

Answer 2

To write userscripts, you start with a js file that is named like yourfile.user.js. Sample content below:

// ==UserScript==
// @name         script-name
// @version      0.1
// @date         yyyy-mm-dd
// @description  description-of-the-script
// @author       John Doe
// @namespace    http://www.foobar.com
// ==/UserScript==

(function (){
  // your js code here

  // this is how you access the global vars in the page
  unsafeWindow.foo = bar;
});

With greasemonkey activated in Firefox browser, when you open this js file in browser, it will prompt you to install it. Install and refresh page to execute it.

For more details, see the link shared by fserb.