Take the 2-minute tour ×

I have some Javascript code.
I want to trace errors and debug it.
how to do it ?

share|improve this question
Debugging is usually done with a debugger... which is present in almost every modern browser. Try pressing F12 or looking over the menus. –  DCoder Sep 12 '12 at 7:15
Which browser do you use? (IE's forbidden) –  sp00m Sep 12 '12 at 7:15
Mozilla Firefox –  H H F Sep 12 '12 at 7:27
add comment

3 Answers

up vote 2 down vote accepted

It used to be that debugging in javascript was quite limited. You could post alerts to indicate variable states or print information to the web page. In the case of syntax error, it would simply not execute all the code (meaning you had to place alerts prior to the error to know where it was).

Thankfully, browsers have caught up. Firebug is very useful as well as Chrome's developer tools which both use breakpoints, expression evaluation, as well as a series of other useful tools for debugging in-browser. I would suggest you look into these. I believe also internet explorer has a developer tools section, but I've found that it isn't to my liking, however you're free to use whatever you need/require.

share|improve this answer
add comment

It depends on the browser:

Most of these tools are accessible via these keyboard shortcuts:

  • F12

Look for the "Console" Tab. There the browser prints various errors like JavaScript errors, resource not loaded errors etc. To manually write to the console, most browsers offer the console object which hosts functions for the console. Most commonly used is console.log('text').

share|improve this answer
I have already installed firebug in firefox then how to use it ? –  H H F Sep 12 '12 at 7:24
@HHF look for the console tab. There the browser prints various errors, including JS errors. –  Joseph the Dreamer Sep 12 '12 at 7:26
add comment

Google Chrome

F12 -> console.

in code use: console.log(variables);

share|improve this answer
add comment

Your Answer


