JSTerm, an experimental Firefox add-on for JavaScript developers, has hit version 2.0.

The JSTerm Firefox add-on — not to be confused with the HTML5 Telnet Emulator by the same name — adds a “jsterm” button to Firefox’s Developer Toolbar. Click the button and you’ll get a JavaScript terminal for live coding, prototyping and quick JavaScript experiments. JSTerm behaves like a typical shell terminal with history, tab completion and plenty of key bindings.

Version 2.0 offers performance improvements, a new option to undock the terminal into its own window, global history shared across sessions and support for OS X’s fullscreen mode.

To try out JSTerm you’ll need Firefox 16 (currently in the Beta channel) since JSTerm uses the newGraphical Command Line Interface we covered in our Firefox 16 beta review. JSTerm also takes advantage of the built-in Firefox Source Editor to highlight JavaScript and a sandbox to eval JavaScript.

If you’re thinking there are already several tools for Firefox that cover this ground, well, you’re right. The built-in Scratchpad and WebConsole both offer similar tools, though neither is quite as nice for quick prototyping and experimenting. Developer favorite Firebug also has a Console for JavaScript developers, but it lacks the nice syntax highlighting you’ll find in JSTerm.

For more details on JSTerm and a changelog of everything that’s new in this release, check out Mozilla developer Paul Rouget’s blog. To have a look at the code behind JSTerm, head to GitHub.