Firefox for Android interprets JavaScript directly, without the need for any add-on.

JavaScript is enabled by default when you first install Firefox, so usually you do not need to turn it on. If you want to check, I will list the steps at the end.

If you load the following test page from my website and scroll down to the JavaScript test section, does it show information about your browser? If JavaScript is turned off, it will show this message in two sections: "JavaScript is not executing on your browser for this page."

https://jeffersonscher.com/res/jstest.php

Sometimes sites will report that JavaScript isn't running or isn't working if something is missing or blocked. It's really just their best guess. Two examples would be:

• Plugin such as the Flash player is not available
• Content filtering extension (e.g., ad blocker) stripped something out

If you can share the address of the page, someone could take a look (assuming no login is required).

To check your JavaScript setting on Firefox for Android:

In the Awesomebar, type or paste about:config and tap the Go arrow. You may want to bookmark this page if you like to tinker with settings.

Type jav into the search box and pause while Firefox filters the list to show preferences that contain jav.

Check under javascript.enabled to confirm that it says true. If it says false and shows a Reset button, tap Reset to restore the value to true.

Thx a lot for your help. The thing is that i need to unlock a locked website and i read somewhere that i should make sure the bubble with "Enable JavaScript" isn't on.

The instructions are to disable JavaScript to get into that site? Unfortunately, this is a global setting and not a site-by-site setting. If you want to try it, you can use about:config to "toggle" javascript.enabled to false in one tab (tap the preference to make the Toggle button appear), then test the site in another tab. When you're done with that site, you can return to the first tab and reset javascript.enabled back to true so other sites will work normally.