Debugging async issues: when tests pass but code fails

Hot take: Console.log is actually a perfectly fine debugging tool. (hear me out) I spent 20 minutes debugging a React bug last week. A senior dev fixed the same bug in 2 minutes. Same experience. Same skills. Same code. None of that is why I'm posting this. Here's what actually happened: I was guessing. Adding logs. Refreshing. Checking console. Adding more logs. Repeating this cycle like a broken record. He wasn't guessing. He set one breakpoint. Stepped through 3 lines. Saw the exact problem. Done. The difference wasn't intelligence. It was tooling. I've been coding for years and never properly learned the debugger. Not because I'm lazy. Because console.log "worked." But "works eventually" isn't the same as "works efficiently." That's not on any bootcamp curriculum. No tutorial mentions this. Everyone just uses console.log because everyone else does. What I actually got from learning the debugger wasn't speed. It was understanding. I stopped guessing why my code breaks. I started seeing exactly how it executes. I stopped being reactive. I started being intentional. If you're still spamming console.log to fix bugs, you're not bad at debugging. You just don't know there's a better tool. Try setting ONE breakpoint this week instead of adding console.log. Just once. See what happens. Your future self (the one who debugs in minutes, not hours) will thank you. Full breakdown: https://lnkd.in/g2bbeRkg 🔥 #WebDevelopment #JavaScript #Debugging #DeveloperTools #CodingTips #Programming #SoftwareEngineering #LearnToCode #WebDev #TechCareer #JuniorDeveloper #CodeNewbie #100DaysOfCode #DevCommunity #ReactJS #3Qverse

Most people think the Event Loop just "manages async code." It actually plays favourites. I assumed every callback waited in the same line. Turns out, there are two queues — and they don't get equal treatment. The moment the call stack goes empty, the Event Loop doesn't just grab the next available function. It checks the Microtask Queue first — always. 𝐏𝐫𝐨𝐦𝐢𝐬𝐞𝐬 𝐚𝐧𝐝 𝐟𝐞𝐭𝐜𝐡() 𝐜𝐚𝐥𝐥𝐛𝐚𝐜𝐤𝐬 𝐥𝐢𝐯𝐞 𝐡𝐞𝐫𝐞. 𝐓𝐡𝐞𝐲 𝐜𝐮𝐭 𝐭𝐡𝐞 𝐥𝐢𝐧𝐞, 𝐞𝐯𝐞𝐫𝐲 𝐬𝐢𝐧𝐠𝐥𝐞 𝐭𝐢𝐦𝐞. Regular callbacks — button clicks, setTimeout — wait in the Callback Queue. They only get their turn once the Microtask Queue is fully drained. So the hierarchy is clear: → Call Stack executes → Microtask Queue gets priority when stack empties → Callback Queue runs only after microtasks are done One event loop. Two queues. One clear winner. Next time your async code behaves unexpectedly — check which queue it's sitting in. 🔍 → Agree or disagree? Tell me below. #BuildingInPublic #JavaScript #SoftwareEngineering #DeveloperJourney #LearningInPublic #Programming #TechCommunity #WebDevelopment

Debugging isn’t about clicking randomly until something works… it’s about thinking clearly until the problem reveals itself. From scattered guessing → to structured thinking: • Strategic logs • DevTools mastery • Explaining your code (yes… even to a rubber duck 🦆) That “aha” moment? It’s not luck. It’s process. Debug smarter, not harder. #Debugging #SoftwareEngineering #ProgrammingLife #WebDevelopment #DevTips #CodingLife #Developers #TechCareer #LearnToCode #CleanCode #ProblemSolving #DevTools #JavaScript #100DaysOfCode #CodingTips

The "this" Keyword: Predictable or a Trap? 🧐 Most devs think they understand this, until it returns undefined. Can you guess the output of this simple object? const obj = { a: 10, f: function () { return this.a; }, }; console.log(obj.f()); The answer seems easy... but do you know what happens to this if we change that function to an Arrow Function? 🤯 In my latest video, I break down exactly how execution context works so you never have to guess again. #JavaScript #WebDev #CodingTips #SoftwareEngineering #Programming

🐞 Debugging in JavaScript — A Practical Approach 1. Identify the Issue Error message or unexpected output 2. Reproduce the Bug Make sure it happens consistently 3. Inspect the Code • Use console.log() smartly • Use DevTools (breakpoints > guessing) 4. Find the Root Cause Common reasons: • Undefined / null values • Async issues (Promises, APIs) • Scope & hoisting problems 5. Fix & Keep It Simple Don’t over-engineer the solution 6. Test Properly Check edge cases + different inputs #JavaScript #Debugging #Development #Coding

⚡ 42 seconds → 1 second. This is what happens when Rust enters your JavaScript build pipeline. We migrated our FE linting pipeline from ESLint + 9 plugins to oxlint. Here's what we measured: ESLint v9 + 9 plugins = 42s oxlint 162 rules = 1s Over 6k files, tested on Apple M5 Pro. 42× speedup on a single run, the delta compounds in CI and watch mode. Migration path was straightforward: most ESLint rules had direct equivalents. A few gaps required minor workarounds, nothing blocking. If your lint step is a bottleneck in local DX or CI pipelines, this is worth evaluating seriously. https://lnkd.in/eNQkNqu4 #JavaScript #DeveloperExperience #Rust #oxlint #CI

Impure Function Vs Pure Function If your code behaves unpredictably and your unit tests feel like a constant battle against global variables, the problem might lie in the "purity" of your functions. 🧠🌐 In the TypeScript and JavaScript ecosystem, the concept of Pure Functions is a cornerstone of sustainable code. But what exactly defines a function as "pure"? Determinism: For the same arguments, it ALWAYS returns the same result. No Side Effects: It does not change anything outside its own scope—no external variables, database writes, or logs. Conclusion: Writing predictable code is a clear sign of technical maturity. Have you been prioritizing pure functions in your projects, or are you still dealing with legacy side effects? #cleancode #typescript #webdev #programming #softwarearchitecture

📚 New article just published on SYUTHD! 🔖 Mastering Local-First Frameworks: The 2026 Guide to Building With PGLite and CRDTs 🏷️ Category: JavaScript Frameworks 📖 Full article → https://lnkd.in/gMuajsA2 👉 Follow our page for more tech tutorials: https://lnkd.in/gsJDptPM 💬 Telegram: https://t.me/nisethtechno 👍 Facebook: https://lnkd.in/gsKv3Dyn #JavaScriptFrameworks #Tech #Tutorial #Programming #TechBlog #2026

Closures in JavaScript felt confusing, until they didn’t 👇 At first, it’s hard to understand how a function can “remember” variables even after execution. But that’s exactly what closures do. A closure is created when a function retains access to its lexical scope, even after the outer function has finished executing. Even though `outer()` has finished execution, the inner function still has access to `count`. That’s the power of closures. They are widely used for: • Data encapsulation • Maintaining state • Creating reusable functions Understanding closures makes many JavaScript patterns much clearer. #JavaScript #Closures #FrontendDevelopment #SoftwareEngineering #Programming

I spent HOURS debugging… and the bug was just ONE line. 😅 Everything looked fine. No syntax errors. No warnings. But the output? Completely wrong. console.log([] == false); // true console.log([] === false); // false Wait… what? 🤯 How can the same values give different results? Then it hit me — one of JavaScript’s most confusing concepts: 👉 Type Coercion Here’s what’s happening behind the scenes: "[] == false" ➡ JavaScript converts both values ➡ becomes "0 == 0" ➡ ✅ true "[] === false" ➡ Strict comparison (no conversion) ➡ ❌ false Same values. Different rules. Completely different results. ⚠️ This is where many bugs are born — not because we don’t know JavaScript… but because JavaScript behaves unexpectedly. 💡 Lesson (relearned the hard way): Always prefer "===" over "==" ✔ "===" → checks value + type ❌ "==" → tries to be “smart” (and gets risky) Sometimes debugging isn’t about writing more code… it’s about understanding how the language actually works. Have you ever faced a bug that made you question everything? 👇 #JavaScript #Debugging #WebDevelopment #Programming #Developers #Coding #SoftwareEngineering #LearnToCode #TechLife