Step Through JavaScripts with Firefox Developer Tool Debugger

* Start Firefox and browse to your page
* Open Firefox Developer Tool with one of following two methods:
– Press F12
– Select Tools > Web Developer > Debugger

* Reload your page by pressing F5
* Find and select you JavaScript source file, e.g. common.js
* Click the line number where you want to set break point

* Reload your page by pressing F5 again
* Web page will stop at your break point
* Click the pause icon:

* Step through icons are enabled:

* You can now step over, step into, step out your Javascript code
* Inspect variables:
– Local variable (Function scope) values
– Global variable (Global scope) values