The use of JavaScript on your Firefox browser is virtually crucial because it enables the best use of modern websites such as Gmail, Facebook, YouTube, and more. What happens if I disable JavaScript on Mozilla Firefox? If the 'javascript.enabled' is set to 'true,' then your JavaScript is working correctly. Type in 'javascript' into this search bar. As you type this, every JavaScript-based setting appear. On clicking the 'Accept the Risk and Continue' button, a search feature will appear. To do that, simply input 'about:config' into the Address Bar of your Firefox browser and press the Enter key on your keyboard. Next, accept the warning about changing advanced settings by clicking the 'I'll be careful, I promise' button. On Mozilla Firefox, JavaScript is enabled by default, but you can check it reasonably quickly to verify if it is working correctly. How do I know if JavaScript is working on Mozilla Firefox? In fact, it should only take you only a minute or so to complete. Enabling JavaScript in your Firefox browser is an easy process. It powers most of the dynamic features you see on web pages, including button clicks, navigations, and form submissions. JavaScript is a popular programming language that's essential for modern websites to function correctly on Mozilla Firefox. Why do I need JavaScript enabled on Mozilla Firefox?