I've recently been developing a new web based application which relies heavily on AJAX and prototype.js.  Unfortunately, developing advanced javascript applications often requires much inserting of manual alerts in lieu of watch variables and proper debugging. 

Now, I've started to use Firebug which is an excellent debugging tool for firefox.  It provides a raft of excellent debugging features directly into the firefox browser ( Firebug lite is available for Opera, IE and Safari too).  These include:

  • Integrated javascript debugging, syntax errors take you directly to the offending line
  • Profiling – see how fast your scripts are
  • Monitor network activity
  • Edit/tweak CSS
  • and many more…

This tool is excellent and is just what i've been looking for as an IDE for Javascript.  Get involved!