debugging

name	debugging
description	Systematic debugging techniques, profiling, and troubleshooting patterns.
globs	["**/*.js","**/*.ts","**/*.py","**/*.java","**/*.go","**/*.rs"]
alwaysApply	["**/debug*","**/error*"]
priority	90
tags	["workflow"]

Debugging Best Practices

Systematic Approach

1. Reproduce the issue consistently
2. Isolate the problem (binary search)
3. Form a hypothesis
4. Test the hypothesis
5. Fix and verify the fix doesn't break anything

JavaScript/Node.js

• Use debugger statement + Chrome DevTools
• Use node --inspect for Node.js debugging
• Use console.trace() for call stacks
• Use console.table() for arrays/objects
• Check network tab for API issues

Common Issues

• Off-by-one errors in loops
• Null/undefined access (use optional chaining)
• Async race conditions (use proper awaiting)
• Memory leaks (check event listeners, closures)
• Circular dependencies (check import order)

Performance Debugging

• Use browser Performance tab
• Use console.time() / console.timeEnd()
• Profile memory with heap snapshots
• Check for unnecessary re-renders (React Profiler)
• Use flame graphs for CPU profiling

Error Handling

• Always log the full error stack
• Use structured error types
• Add context to rethrown errors
• Use error boundaries (React) or global handlers
• Monitor errors in production (Sentry)