Question

I get an error message from Firefox “Unresponsive script”. This error is due to some javascript I added to my page.

I was wondering if the unresponsiveness are caused exclusively by code loops (function calling each other cyclically or endless “for loops”) or there might be other causes ?

Could you help me to debug these kind of errors ?

thanks

Answer 1

According to the Mozzila Knoledgebase:

When JavaScript code runs for longer than a predefined amount of time, Firefox will display a dialog that says Warning: Unresponsive Script. This time is given by the settings dom.max_script_run_time and dom.max_chrome_script_run_time. Increasing the values of those settings will cause the warning to appear less often, but will defeat the purpose: to inform you of a problem with an extension or web site so you can stop the runaway script.

Furthermore:

Finding the source of the problem

To determine what script is running too long, click the Stop Script button on the warning dialog, then go to Tools | Error Console. The most recent errors in the Error Console should identify the script causing the problem.

Checking the error console should make it pretty obvious what part of your javascript is causing the issue. From there, either remove the offending piece of code or change it in such a way that it won’t be as resource intensive.

EDIT: As mentioned in the comments to the author of the topic, Firebug is highly recommended for debugging problems with javascript. Jonathan Snook has a useful video on using breakpoints to debug complex pieces of javascript.