Web Dev Simplified on YouTube · Open on YouTube
First build · Advanced beginner · Lesson 28 of 98 · 35 min video, then about 2 hours of practice
Debugging systematically instead of guessing
After this you can reproduce a bug, form a hypothesis, test it with a debugger or targeted logging, and confirm the fix.
Why it matters
Debugging is most of the job and it is rarely taught. The method is the scientific one: reproduce the bug reliably, narrow down where it happens, form a hypothesis, test it, fix, and confirm. Use the browser devtools and Node's debugger with breakpoints rather than scattering `console.log` everywhere. Keep a short bug journal during this project: symptom, cause, fix. Patterns will appear quickly. Trap: changing several things at once until it works. You learn nothing and often introduce a new bug.
How to use this resource
A practical approach to debugging as a skill, not a set of tricks.