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Tech Guides for Everyone

Enable or disable JavaScript in Mozilla Firefox (LINUX)

[youtube=https://www.youtube.com/watch?v=-K07wrXPqwE]

This guide will show you how to enable or disable JavaScript in Mozilla Firefox running on Linux, specifically Ubuntu. Mozilla have removed the ability to easily switch JavaScript on or off using the Preferences window, but you can still do it via the about:config method.

Watch the video above or follow the text guide below.

Enable/disable JavaScript in Firefox (LINUX)

  1. Open Firefox
  2. Type about:config in the address bar and press Enter
  3. Please note if your PC or device came with Firefox pre-installed, by clicking the I’ll be careful, I promise button may void your warranty
  4. Otherwise, click on the I’ll be careful, I promise button
  5. Only alter the following values, do not alter any other values or Firefox may not work
  6. In the search box, type javascript.enabled to find the preference option of the same name
  7. Right-click on the javascript.enabled option and select Toggle from the menu
  8. The javascript.enabled option should now be in bold text and the Value column should read as false
  9. Restart Firefox, then visit whatismyipaddress.ricmedia.com to confirm JavaScript is disabled
  10. To re-enable JavaScript, follow the steps above and Toggle the javascript.enabled option back to Value=true

Enable or disable JavaScript in Chromium (LINUX)

[youtube=https://www.youtube.com/watch?v=2PVxx75VJQo]

Today I will show you how to turn JavaScript on or off in Chromium web browser running on Ubuntu Linux. Although it is better to leave JavaScript enabled to make sure a smooth and feature rich browsing experience, there are times when you need to disable it (testing website CSS fallback etc).

Watch the video above or follow the text guide below.

Enable or disable JavaScript in Chromium

  1. Open Chromium
  2. Click on the Chromium Menu Chromium Menu at the top-right of the app window
  3. Click on the Settings menu item
  4. Scroll down and click on the Show advanced settings… link
  5. Look for the Privacy heading
  6. Click on the Content settings button
  7. A small window should now be visible
  8. Look for the JavaScript heading
  9. Choose between Allow all sites to run JavaScript or Do not allow any site to run JavaScript options
  10. You can also make exceptions to allow or disallow any website by clicking on the Manage exceptions button
  11. For example: If I chose the Allow all websites to run JavaScript option, we can make an exception to block JavaScript for badsite.com
  12. Or if I chose the Do not allow any site to run JavaScript option, we can make an exception to allow JavaScript for goodsite.com
  13. When you have finished choosing your options, click the Done button, then close the settings window

What is JavaScript?

Firstly let’s define what a script is before we learn about JavaScript.

A script is a set of instructions given to a browser/server that is essentially an “active” command, in other words, it does things instead of just static HTML element. Let’s go through a few examples:

  • lets say you want to contact a webmaster to ask a question, most of the time you’ll be presented with a form to fill out. When you have finished filling out the form, there will be a button that says “Submit” or “Send” (see figure 1.a below), when you click this button all the information in the form is sent to a script that lives on the web server. This script will (among other things) make a record of your details in a database, format the data into an email and send it to the webmaster. This type of script is called a form processor and is also an example of a Server side script because all the actions takes place on the web server.
Example form that uses JavaScript for validation
Example form that uses JavaScript for form field validation
  • Now lets take the same situation except this time you forget to choose your country and it is left on “Please Select”, you click the Submit button, but instantly there is a little alert box advising you of your mistake (see figure 1.b below). This is JavaScript and is an example of Client side scripting because this action takes place inside your browser, not the server.
Example of a JavaScript alert box
Example of a JavaScript alert box activating during form validation

JavaScript

As you have probably guessed, JavaScript is a client side scripting language processed by your browser. Most browsers have a built-in JavaScript “Engine” or interpreter that reads the instructions given on a webpage and acts upon them. The script in the last example basically said If the user forgets to enter their country, make an alert box and tell them of their mistake.

JavaScript can do a lot more too, for instance: validate forms, visual effects like fade, grow and blind, rollover menus and with Ajax pretty much anything. JavaScript is also quite easy to program, has been around since the mid 90’s and is widely used, so that’s why you have probably heard about it. You’ve the option to turn JavaScript on or off in your browser and by default most browsers have it enabled, however it’s recommended that you leave it enabled so you can enjoy all the web has to offer. If you need help checking your browsers JavaScript status, visit our guide on how to enable or disable JavaScript.

This guide’s intended to give a conceptual overview of JavaScript, if you’re interested in studying it just visit W3Schools for complete tutorials and reference.