MDN’s new design is in Beta! A sneak peek:

Open the debugger

This page describes the JavaScript Debugger as it appears before Firefox 52.

See what it looks like from Firefox 52 onwards.

To open the debugger press the menu button ( new fx menu ), press "Developer", then select "Debugger". Or use the keyboard shortcut:

  • Control-Shift-S in Windows and Linux
  • Command-Option-S on a Mac

The Toolbox will appear at the bottom of the browser window, with the Debugger activated. Here's what it looks like when you first open it:


Document Tags and Contributors

 Contributors to this page: wbamberg
 Last updated by: wbamberg,