MDN wants to learn about developers like you:

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

See what it looks like from Firefox 52 onwards.

To set a conditional breakpoint, activate the context menu while on the line you want to break at in the source pane, and select "Add conditional breakpoint". Then enter the conditional expression in the popup that appears:

Conditional breakpoints get an orange arrow in the source pane:

To edit the condition, or to add a condition to a normal breakpoint, activate the context menu and select "Configure conditional breakpoint":

Document Tags and Contributors

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