To check that JavaScript is enabled on Firefox for Android, you can use the about:config page. There is no dialog for this, so you need to do a little work under the covers. Here's how:

In the address bar , 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.

Should this be in https://support.mozilla.org/en-US/questions/mobile?

moved to the Firefox for Android queue

Duplicate of /questions/1094018 since it answered the question unless poster really meant JavaScript.