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How do you check to see if JavaScript is enabled in Firefox?

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I never knew how to enable Javascript in Firefox or to check to see if Javascript is enabled in Firefox because several sites require Javascript in order to function properly. How do I enable it?

I never knew how to enable Javascript in Firefox or to check to see if Javascript is enabled in Firefox because several sites require Javascript in order to function properly. How do I enable it?

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Hi Lisette, JavaScript is enabled by default. If you think it might not be -- because half of the web is telling you so -- you can check here:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful or accepting the risk.

(2) In the search box above the list, type or paste javas and pause while the list is filtered

(3) If the javascript.enabled preference is bolded and "modified" to false, double-click it to restore the default value of true


If websites still tell you JavaScript is disabled:

Double-check content blockers: Firefox's Content Blocking feature and extensions that counter ads and tracking may break websites that embed third party content (meaning, from a secondary server).

(A) Do you see a shield icon toward the left end of the address bar, near the lock icon? More info on managing the Tracking Protection feature in this article: Content Blocking.

(B) Extensions such as Adblock Plus, Blur, Disconnect, Ghostery, NoScript, Privacy Badger, uBlock Origin or uMatrix should provide toolbar buttons to manage blocked content in a page. There may or may not be a number on the icon indicating the number of blocked items; you may need to click the button to see what's going on and test whether you need to make an exception for this site.

Test in Firefox's Safe Mode: In its Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is not running: Hold down the Shift key when starting Firefox. (On Mac, hold down the option/alt key instead of the Shift key.)

If Firefox is running: You can restart Firefox in Safe Mode using either:

  • "3-bar" menu button > "?" Help > Restart with Add-ons Disabled
  • (menu bar) Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement?

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Hi Jscher2000, you are so helpful. I did as you recommended and noticed that the JavaScript is enabled; however, there are several items on the list that say "False." Should I be concerned about that? Thank you.

~ Lisette

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Hi Lisette, as a general rule, I don't recommend changing default values unless you look up first what they do.