JavaScript Synchronous Execution Leads to Infinite Loop

Day 9 of 100 🔥 We called greet() and used num BEFORE declaring them. One works perfectly. One gives a surprise. 😱 Comment down 👇 No googling! Hint: JavaScript secretly moves some things to the top of the code before running it. But it doesn't move everything the same way! 👀 This concept is called HOISTING — and it's one of the most asked JS interview questions ever! Full explanation tonight in the comments! #100DaysOfCode #JavaScript #CodingInterview #JavaScriptTips #WebDevelopment

🚀 JavaScript Last-Minute Cheat Sheet — Perfect Before Interviews & Coding Rounds 🔥 Variables & Scope • "let" & "const" over "var" • Block scope matters • Avoid global variables ⚡ Functions • Arrow functions → shorter syntax • Default parameters save time • Closures = function + lexical scope 🧠 Async JavaScript • Callbacks → Promises → "async/await" • Use "try...catch" for error handling • "Promise.all()" for parallel execution 📦 Arrays & Objects • "map()", "filter()", "reduce()" = must know • Spread "..." & Destructuring simplify code • Optional chaining "?." prevents crashes 🎯 DOM & Events • "querySelector()" is your best friend • Event delegation improves performance • Debounce & throttle for optimization 💡 Pro Tip Understand concepts, not just syntax. Clean code + problem-solving mindset = real JavaScript mastery. Learn more From w3schools.com ✨ #JavaScript #WebDevelopment #FrontendDeveloper #CodingInterview #100DaysOfCode

🚀 Day 963 of #1000DaysOfCode ✨ Difference Between var, let & const in JavaScript These three look similar… but behave very differently in real-world code. In today’s post, I’ve broken down the differences between `var`, `let`, and `const` in a simple and practical way, so you can understand when and why to use each of them. From scope and hoisting to re-declaration and mutability, these concepts directly impact how your code behaves — and are often the reason behind many unexpected bugs. I’ve also explained common mistakes developers make while using them, so you can avoid those pitfalls in your own projects. If you’re writing modern JavaScript, having clarity on this is absolutely essential. 👇 Which one do you use the most — `var`, `let`, or `const`? #Day963 #learningoftheday #1000daysofcodingchallenge #FrontendDevelopment #WebDevelopment #JavaScript #React #CodingCommunity #JSBasics

🚨 𝗠𝗼𝘀𝘁 𝗱𝗲𝘃𝗲𝗹𝗼𝗽𝗲𝗿𝘀 𝗴𝗲𝘁 𝘁𝗵𝗶𝘀 𝘄𝗿𝗼𝗻𝗴 👇 JavaScript variables look simple… Until they silently break your logic 😵 🧠 𝗧𝗿𝘆 𝘁𝗵𝗶𝘀: 𝑐𝑜𝑛𝑠𝑜𝑙𝑒.𝑙𝑜𝑔(𝑎); 𝑣𝑎𝑟 𝑎 = 10; 𝑐𝑜𝑛𝑠𝑜𝑙𝑒.𝑙𝑜𝑔(𝑏); 𝑙𝑒𝑡 𝑏 = 20; 𝗪𝗵𝗮𝘁 𝘄𝗶𝗹𝗹 𝗯𝗲 𝘁𝗵𝗲 𝗼𝘂𝘁𝗽𝘂𝘁? Take a guess before scrolling… 👇 . . . . . . ✅ 𝗔𝗻𝘀𝘄𝗲𝗿: undefined ReferenceError: Cannot access 'b' before initialization 💡 𝗦𝗶𝗺𝗽𝗹𝗲 𝗘𝘅𝗽𝗹𝗮𝗻𝗮𝘁𝗶𝗼𝗻 JavaScript behaves differently for var and let: 👉 var is hoisted and initialized with undefined 👉 let is also hoisted, BUT it stays in a “𝗧𝗲𝗺𝗽𝗼𝗿𝗮𝗹 𝗗𝗲𝗮𝗱 𝗭𝗼𝗻𝗲” until the line where it’s defined So: • a exists → prints undefined • b exists but is 𝗻𝗼𝘁 𝗮𝗰𝗰𝗲𝘀𝘀𝗶𝗯𝗹𝗲 𝘆𝗲𝘁 → throws error 🎯 𝗞𝗲𝘆 𝗧𝗮𝗸𝗲𝗮𝘄𝗮𝘆𝘀 • var → function scoped + can lead to unexpected bugs • let → block scoped + safer to use • Always prefer let & const in modern JavaScript 🔥 𝗗𝗶𝗱 𝘆𝗼𝘂 𝗴𝗲𝘁 𝗶𝘁 𝗿𝗶𝗴𝗵𝘁? Be honest 😄 💬 Comment your answer before you saw the solution 🔖 Save this for interview prep 💡 Part of my #FrontendRevisionMarathon — breaking down Frontend concepts daily 🚀 🚀 Follow Shubham Kumar Raj for more such content. #javascript #frontenddeveloper #codinginterview #webdevelopment #learnjavascript #100daysofcode #programming #interviewprep #CareerGrowth #SowftwareEngineering

Most developers don't know how their JavaScript code is executed.   V8 (Chrome's engine) compiles your code through 4 tiers -- bytecode interpreter, baseline JIT, mid-tier optimiser, and a top-tier compiler that generates near-C++ machine code. The engine watches how your code runs and recompiles hot paths with increasingly aggressive optimisations.   This is why consistent object shapes make code faster, why eval() kills performance, and why a function that runs 10,000 times is faster than one that runs 10 times -- the engine literally rewrites it.   Understanding this pipeline is one of the most-asked concepts in front end interviews -- and most candidates can't explain it beyond "V8 compiles JavaScript."   How deep does your understanding of JS engines go?   Practice JavaScript interview questions with detailed solutions: https://lnkd.in/gNxCH3e3 #JavaScript #V8 #FrontEnd #WebDevelopment #InterviewPrep #GreatFrontEnd

Day 4 — Today was the day the web stopped being static for me. DOM manipulation. Sounds scary. Actually really fun. Built a simple to-do list from scratch — no libraries, no frameworks. Just vanilla JS touching the page directly. The moment I typed something in an input field and saw it appear on screen because of code I wrote... that feeling doesn't get old. Key thing I learned: event delegation. Instead of adding an event listener to every single element, you add one to the parent and let events bubble up. Cleaner and way more efficient. Also — preventDefault() is your best friend in form handling. Took me an embarrassing number of refreshing pages to learn that lesson. What was your first "I built this" moment in coding? #javascript #webdev #frontenddeveloper #learninpublic

🚀 Day 4/30 – JavaScript Challenge Solved: Counter II (LeetCode 2665) Today’s problem was all about understanding closures and how functions can maintain their own state in JavaScript. What I learned: 1.How closures help preserve variable values across function calls 2.Creating multiple operations (increment, decrement, reset) using a single function 3.Clean use of arrow functions for concise code Approach: I created a function that stores the initial value and returns an object with three methods: 1.increment() -> increases value 2.decrement() -> decreases value 3.reset() -> resets to initial value All of this works because of closure, where the inner functions still remember the variable n. Key Insight: Closures are powerful when you need to encapsulate data and control how it’s modified — a very common pattern in real-world JavaScript applications. Consistency is the real game here 🔥 Let’s keep building, one day at a time. #Day4 #30DaysOfCode #JavaScript #WebDevelopment #CodingChallenge #LeetCode #Closures #LearningJourney

🚫 Still confused why this throws an error in JavaScript? 👉 You declared the variable… but still getting a ReferenceError? Welcome to the Temporal Dead Zone (TDZ) 👇 Most developers think variables are available right after declaration… But with let and const, that’s NOT true. ⚠️ There’s a hidden phase: 👉 Variable is created 👉 BUT not initialized yet 👉 You CAN’T access it That gap is called 👉 TDZ 💡 Why this matters: • Prevents unexpected bugs • Forces cleaner code • Makes JavaScript more predictable 🔥 Real rule: "Variables exist before execution, but you can't use them until initialization." 💻 If you're preparing for interviews or improving JS fundamentals — this is MUST KNOW. 👇 Comment “TDZ” if you understood it 🔁 Repost to help other devs #javascript #webdevelopment #frontend #reactjs #coding #programming #100daysofcode #developer #softwareengineering #learncoding

🚀 JavaScript Problem-Solving Practice 💻 Today, I worked on improving my logic building skills with some interesting problems 👇 🔹 Minimum Coins Problem Used slice() + reduce() to find the minimum number of elements forming a target sum. 🔹 Array Transformation Replaced even indices with minimum value and sorted odd indices using sort(). 🔹 First Non-Repeating Character Used an object (frequency count) to find the first unique character in a string. 💡 Key Learnings: ✔️ Better understanding of slice(), reduce(), sort() ✔️ Improved array & string manipulation ✔️ Strengthened problem-solving approach Consistency is the key 🔑✨ #JavaScript #ProblemSolving #CodingPractice #FrontendDevelopment

🚀 JavaScript Last-Minute Cheat Sheet — Perfect Before Interviews & Coding Rounds 🔥 Variables & Scope • "let" & "const" over "var" • Block scope matters • Avoid global variables ⚡ Functions • Arrow functions → shorter syntax • Default parameters save time • Closures = function + lexical scope 🧠 Async JavaScript • Callbacks → Promises → "async/await" • Use "try...catch" for error handling • "Promise.all()" for parallel execution 📦 Arrays & Objects • "map()", "filter()", "reduce()" = must know • Spread "..." & Destructuring simplify code • Optional chaining "?." prevents crashes 🎯 DOM & Events • "querySelector()" is your best friend • Event delegation improves performance • Debounce & throttle for optimization 💡 Pro Tip Understand concepts, not just syntax. Clean code + problem-solving mindset = real JavaScript mastery. Learn More From w3schools.com , JavaScript Mastery ✨ Follow ABDUL REHMAN ♾️ For More Usefull Contents 🔥 #JavaScript #WebDevelopment #FrontendDeveloper #CodingInterview #100DaysOfCode