Javascript debugging in Firefox 3?

How can one 开发者_运维知识库find Javascript errors in Firefox 3? IE shows it by default, but how do you do it in Firefox? I do have Firebug, but no idea where to start?

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Open the error console.

Tools > Error Console or Ctrl+Shift+J.

(This is a standard feature in Firefox, you don't need Firebug to use it.)

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just open firebug, if there is an error it shows you the error in the console

maybe you have to enable the console first