You've written code that should work. You've checked it twice. Yet somehow, when you run it, something goes wrong. The error message might as well be written in ancient Greek. Your instinct screams: change random things until it works.

This instinct will betray you. Random changes lead to random results, and even if you stumble onto a fix, you won't understand why it worked. Real debugging isn't about luck—it's about investigation. The good news? You already know how to think like a detective. You just need to apply those same skills to code.

When something breaks, resist the urge to immediately start fixing. A detective doesn't arrest the first suspicious person they see—they gather evidence first. Your bug has left clues everywhere. Error messages, unexpected outputs, the exact moment things went wrong. Write these down. Seriously.

Start by asking simple questions. What did you expect to happen? What actually happened? When did it start happening—after which specific change? Can you reproduce the problem consistently, or does it appear randomly? Each answer narrows your search.

Error messages deserve special attention. They often look intimidating, but they're actually your bug confessing its location. Read them carefully, especially the line numbers. Google the exact error text if needed. The message "TypeError: cannot read property 'name' of undefined" tells you exactly what happened: you tried to access something that doesn't exist. That's not cryptic—that's helpful.

Takeaway

Collect evidence before forming theories. The quality of your debugging depends on the quality of your observations.

With evidence in hand, you can start forming theories. Not vague hunches like "something's wrong with the loop"—specific, testable hypotheses. "The loop runs one too many times" is testable. "The variable 'count' becomes negative when it shouldn't" is testable.

Test one hypothesis at a time. This is where most beginners go wrong. They change five things, the bug disappears, and they have no idea which change fixed it. Worse, they might have introduced new bugs without knowing. One change, one test, one observation.

Print statements are your simplest testing tool. Add them to show variable values at specific points. "At line 15, count equals 3" tells you whether your theory holds. If count should be 3 and it is, your hypothesis about that variable was wrong. Move on to the next theory. This isn't primitive—it's precise.

Takeaway

A hypothesis isn't useful unless you can test it. Make your theories specific enough that evidence can prove them wrong.

Sherlock Holmes said it best: when you eliminate the impossible, whatever remains must be the truth. Debugging works the same way. Each test that disproves a theory is progress, even though it feels like failure.

Binary search your code. If you have a hundred lines and something's wrong, check the middle. Is the state correct at line 50? If yes, the bug is in lines 51-100. If no, it's in lines 1-50. You've just eliminated half your code with one test. Repeat until you've cornered the bug.

Comment out sections systematically. Does the bug still happen without this function? Without this loop? You're not randomly hacking—you're methodically isolating. When you find the smallest piece of code that still produces the bug, you've found your culprit. Now you understand not just what was wrong, but why. That understanding prevents the same bug from haunting you again.

Takeaway

Every eliminated possibility brings you closer to the answer. Systematic elimination beats random guessing every time.

Debugging feels frustrating because we expect code to just work. But bugs aren't personal failures—they're puzzles waiting to be solved. Every programmer, no matter how experienced, spends significant time debugging. The difference is method, not magic.

Next time something breaks, slow down. Gather your evidence. Form a specific theory. Test it. Eliminate possibilities until only the truth remains. You're not just fixing code—you're training yourself to think systematically. That skill transfers to every problem you'll ever face.