Here are tools for Javascript's debugging.
JavaScript Debuggers : Venkman
If you want to learn how to use Venkman, check this tutorial.
Debugging Ajax in Firefox 1.5 and 2.0
Greasemonkey combined with a script called the XMLHttpRequestDebugging.v1.2.user.js
New and getting popular debugger for Firefox that combines logging
Firebug
For IE
Microsoft Script Editor.
I assume most web-guys use Firebug.
That's it
Disclaimer : Most Tools are introduced in The Book of JavaScript : A Practical Guide to Interactive Web Pages
JavaScript Debuggers : Venkman
If you want to learn how to use Venkman, check this tutorial.
Debugging Ajax in Firefox 1.5 and 2.0
Greasemonkey combined with a script called the XMLHttpRequestDebugging.v1.2.user.js
New and getting popular debugger for Firefox that combines logging
Firebug
For IE
Microsoft Script Editor.
I assume most web-guys use Firebug.
That's it
Disclaimer : Most Tools are introduced in The Book of JavaScript : A Practical Guide to Interactive Web Pages
