What is a good Javascript debugging tool?

Question

Haven't touch javascript for 3 years. Just got a javascript project and wanted to know any new ways or tools emerged these years to debug javascript? I used alert 3 years ago.

I am using IE

Answer 1

Use the Firebug extension for Firefox, or the built-in Web Inspector in any WebKit browser (Chrome or Safari). In IE8, you can use the built-in Developer ToolS.