Firefox offers many handy tools for developers, including integrated web and error consoles as well as a code inspector. It also had Scratchpad, a tool that lets programmers toy with their JavaScript and execute it from right within a Firefox window. Scratchpad's simple interface was quite convenient for developers. Sadly it's no longer available, but that doesn't mean you can't still write and test multi-line JavaScript in Firefox. We show you how.
Scratchpad was removed with the launch of Firefox 72. We have a suitable alternative for testing JavaScript code below.
Using Firefox's Web Console Editor Mode
While Scratchpad is no longer available, Mozilla did introduce a Web Console Editor Mode with Firefox 71+. This is a suitable alternative for writing and testing multi-line JavaScript. Here's how to access it.
Open Tools > Web Developer > Web Console.
You can also access the web console via the keyboard shortcut CTRL+SHIFT+K.
The console appears at the bottom of the screen and shows the current web page's code. Enter the multi-line editing mode by clicking the arrows on the lower left side of the console.
You can also access multi-line editing via the keyboard shortcut Ctrl + B (Cmd + B on macOS).
Type your code into the editor. Use Enter to add new lines, or use CTRL+Enter to run them.