document updated 15 years ago, on Sep 15, 2011

See also: roundup of the state of the art in in-browser debugging across the major browsers.

view Javascript errors — Tools > Error Console

more thorough debugging — Firebug

view Javascript errors — double-click on the exclamation-alert icon in the far lower-left corner

more thorough debugging

IEDevBar (it's only useful for JS debugging starting in IE8)
- built-in to IE8; press F12 or go to Tools > Developer Tools
Microsoft Script Editor (more info)
- separate install
Microsoft Script Debugger
- separate install

view Javascript errors — enable the develop menu, Page > Develop > Show Error Console

more thorough debugging — Web Inspector

view Javascript errors — Page > Developer > JavaScript Console

more thorough debugging — Page icon > Developer > Debug JavaScript (it's text-only)

view Javascript errors — Tools > Advanced > Error Console

more thorough debugging — Dragonfly