This page describes the JavaScript Debugger as it appears before Firefox 52.
The JavaScript Debugger enables you to step through JavaScript code and examine or modify its state to help track down bugs.
You can use it to debug code running locally in Firefox or running remotely, for example in a Firefox OS device or Firefox on Android. See remote debugging to learn how to connect the debugger to a remote target.
User Interface Tour
To find your way around the debugger, here's a quick tour of the UI.
How to
To find out what you can do with the debugger, see the following how-to guides:
- Open the debugger
- Set a breakpoint
- Disable breakpoints
- Step through code
- Break on a DOM event
- Highlight and inspect DOM nodes
- Pretty-print a minified file
- Search and filter
- Set a conditional breakpoint
- Examine, modify, and watch variables
- Use a source map
- Black box a source
- Debug eval sources
- Access debugging in add-ons