Firebug is an extension for the Mozilla Firefox browser that allows you to debug and inspect HTML, CSS, the Document Object Model (DOM) and JavaScript. Though it has many strong features, it’s most known for revolutionizing the way developers debug and profile JavaScript code.
For example, before Firebug, many developers would use the alert() function to see what a variable contains or to find what line the code breaks. With Firebug enabled, you’re told specifically what the error is and which line it comes from. Firebug is an excellent tool for AJAX application developers because it lets you explore and perform on-the-fly edits on the DOM to see what happens when you manipulate Web page elements after a user action.
Aside from its popular JavaScript and DOM functionalities, Firebug can also log network activity to allow you to see detailed results of HTTP connections, inspect and edit HTML on the fly and debug and visualize your CSS。
