How to Disable Script & Runtime Errors in Firefox Browser
The programming of modern websites is more complicated than ever and the extensive scripting work required to create a website with interactive content means that the occasional error will inevitably creep in. Firefox is set up to display an "Unresponsive Script" warning when a script causes the browser to lock up. However, you might prefer to close the browser and re-open it in the event of a script problem, or simply allow the browser to continue running. Disable the unresponsive script warning in Firefox if you do not find it helpful.
Type "about:config" without quotation marks in the address bar at the top of the Firefox window. Press "Enter." You will receive a warning that you are about to enter an advanced area. Click "I'll be careful, I promise."
Type the word "script" into the "Filter" box at the top of the window. On the list of results, you will find an item labeled "dom.max_script_run_time."
Double click "dom.max_script_run_time." A new window labeled "Enter integer value" will appear.
Enter "0" in the box and click "OK." This disables the unresponsive script error completely.
Browse away from the about:config page by entering the address of another website.