How to use the debugger statement in JavaScript

Short answer

The debugger; statement triggers a breakpoint when developer tools are open, pausing execution exactly where you need to inspect state.

Steps

1. Insert debugger in your code: javascript function calculate(x) { const y = x * 2; debugger; // pauses here if DevTools is open return y + 1; }
2. Use conditional debugging: javascript if (user.role === "admin") { debugger; }
3. Combine with source maps for debugging transpiled code.

Tips

• Remove debugger statements before committing to production.
• Use DevTools conditional breakpoints instead of debugger for persistent debugging logic.

Common issues

• debugger has no effect if developer tools are closed.
• Accidentally leaving debugger in production can pause user sessions if DevTools is opened.