Dom.max chrome script run time

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JavaScript that takes a long time to run can make the browser unresponsive. As such, a check is built in to allow long-running scripts to be aborted. That check is now able to differentiate between scripts running in web pages (content) and scripts running in the application’s chrome. This preference determines how long scripts running from chrome are allowed to run before the user can choose to abort the script.

Possible values and their effects

The value is a positive integer, determining the number of seconds of execution (wall time). 0 and negative values are considered “forever.” Default value is 20.

For Thunderbird and SeaMonkey on Mac, the default is 0 since 2012-08-21 trunk build (bug 482811).


  • This preference only controls scripts running with chrome privileges. For scripts with content privileges, see dom.max_script_run_time.

First checked in

2006-07-27 by Johnny Stenback

Has an effect in

  • Mozilla Firefox (nightly builds after 2006-07-27; 2.0)
  • Thunderbird (nightly builds after 2006-07-27; 2.0)
  • SeaMonkey (nightly builds after 2006-07-27; 1.1)

Related bugs

Related preferences