Variables in JavaScript: var, let, const Explained

📚 What I Studied Today – JavaScript Functions & Array Methods Today I strengthened my understanding of some core JavaScript concepts: 🔹 Functions A function is a block of code written once and reused multiple times to perform a specific task. 🔹 Function Definition vs Call - Function Definition: Declares a function with parameters - Function Call: Executes the function using arguments 👉 Parameters = values inside () in definition 👉 Arguments = values inside () in call 🔹 Important Concepts - Parameters act like local variables (accessible only inside the function) - Functions help reduce redundancy (avoid repeating code) - Arrow functions provide a shorter syntax using "=>" 🔹 Callbacks & Higher Order Functions - A callback function is passed as an argument to another function - "forEach()" is a higher order method because it takes a function as input 🔹 Array Methods - "map()" → transforms each element into a new array - "filter()" → selects elements based on a condition - "reduce()" → reduces array to a single value (sum, total, etc.) 🚀 Slowly building a strong foundation in JavaScript! #JavaScript #WebDevelopment #CodingJourney #Learning #MERN

Day 7/100 of JavaScript 🚀 Today’s Topic: Taking input in JavaScript. In browser-based JavaScript, input can be taken using: - "prompt()" - Input fields (DOM) On platforms like LeetCode, input is already provided as function parameters Example: var twoSum = function(nums, target) { // input is already given }; So the focus is on writing logic, not handling input However, some coding platforms (or local environments) do not provide inbuilt input handling. In such cases, we use Node.js Example: process.stdin.on("data", (data) => { const input = data.toString().trim(); console.log(input); }); This allows us to read input from the console Key understanding: - Platforms like LeetCode handle input internally - Other platforms and local setups require manual input handling using Node.js Understanding both approaches is important for coding practice #Day7 #JavaScript #100DaysOfCode

🚀 Day 6/108 – Conditional Statements in JavaScript Continuing my 108-day JavaScript journey — today I learned how to make decisions in code 👇 👉 What are Conditional Statements? They allow us to execute different blocks of code based on conditions. 🧠 Types of Conditional Statements: 🔹 if statement Executes code if a condition is true 🔹 if...else statement Executes one block if true, another if false 🔹 if...else if...else Used to check multiple conditions 🔹 switch statement Used when comparing one value against multiple cases 💻 Example: let age = 18; if (age >= 18) { console.log("You are an adult"); } else { console.log("You are a minor"); } 🧠 Key Insight: Conditions always return either "true" or "false". ⚠️ Quick Note: JavaScript also has truthy and falsy values Falsy values → "false, 0, "", null, undefined, NaN" 🔥 Learning step by step — consistency is everything! How do you usually write conditions — if-else or switch? 👇 #JavaScript #WebDevelopment #CodingJourney #LearningInPublic #100DaysOfCode

Day 4/100 of JavaScript 🚀 Today’s focus: Functions in JavaScript Functions are reusable blocks of code used to perform specific tasks Some important types with example code: 1. Parameterized function → takes input function greet(name) { return "Hello " + name; } greet("Apsar"); 2. Pure function → same input always gives same output, no side effects function add(a, b) { return a + b; } add(2, 3); 3. Callback function → function passed into another function function processUser(name, callback) { callback(name); } processUser("Apsar", function(name) { console.log("User:", name); }); 4.Function expression → function stored in a variable const multiply = function(a, b) { return a * b; }; 5.Arrow function → shorter syntax const square = (n) => n * n; Key understanding: Functions are first-class citizens in JavaScript — they can be passed, returned, and stored like values #Day4 #JavaScript #100DaysOfCode

🚀 Day 979 of #1000DaysOfCode ✨ 4 Useful Number Functions in JavaScript (With Cool Examples) JavaScript provides many built-in number utilities — but most developers only use a few of them. In today’s post, I’ve shared 4 super useful number functions in JavaScript along with some cool and practical examples for each. These functions can help you handle number validation, formatting, and edge cases more effectively in real-world applications. Small utilities like these might look simple, but they can save you time and help you write cleaner and more reliable logic. Once you start using them properly, you’ll notice how often they come in handy while working with data. If you work with numbers, calculations, or user inputs in JavaScript, these functions are definitely worth knowing. 👇 Which JavaScript number function do you use the most in your projects? #Day979 #learningoftheday #1000daysofcodingchallenge #FrontendDevelopment #WebDevelopment #JavaScript #React #CodingCommunity #JSDevelopers

Useful JavaScript Tricks Developers Should Know 🚀 JavaScript has some powerful features that can make your code cleaner and more efficient. Here are a few JavaScript tricks I use regularly: 🔹 Destructuring Extract values from objects easily const { name, age } = user; 🔹 Optional Chaining Avoid undefined errors user?.profile?.name 🔹 Default Parameters Set default values function greet(name = "Developer") { return `Hello ${name}`; } 🔹 Spread Operator Copy arrays or objects const newArray = [...oldArray]; 🔹 Short Circuit Evaluation Cleaner conditional logic isLoggedIn && showDashboard() These small tricks can make your code more readable and efficient. Still learning JavaScript every day 🚀 What’s your favorite JavaScript trick? #JavaScript #FrontendDeveloper #ReactNative #SoftwareEngineer #CodingTips #WebDevelopment

🚀 **Understanding JavaScript Variables Like a Pro (var vs let vs const)** If you're working with JavaScript, choosing the right keyword — `var`, `let`, or `const` — is more important than you think. Here’s a simple breakdown 👇 🔸 **var** * Function scoped * Can be re-declared * Can be re-assigned * Hoisted with `undefined` 👉 Mostly avoided in modern JavaScript due to unexpected behavior. --- 🔹 **let** * Block scoped * Cannot be re-declared in same scope * Can be re-assigned * Hoisted but in Temporal Dead Zone (TDZ) 👉 Best for variables that will change. --- 🔒 **const** * Block scoped * Cannot be re-declared * Cannot be re-assigned * Must be initialized at declaration 👉 Best for constants and safer code. --- 💡 **Pro Tip:** Always prefer `const` by default → use `let` when needed → avoid `var`. --- 📊 The attached diagram explains: * Scope hierarchy (Global → Function → Block) * Memory behavior * Key differences visually --- 🔥 Mastering these fundamentals helps you: ✔ Write cleaner code ✔ Avoid bugs ✔ Crack interviews easily --- #JavaScript #WebDevelopment #Frontend #Coding #Programming #Developers #LearnToCode #Tech #SoftwareEngineering #NodeJs #Json

Built a To-Do List App using JavaScript 🧠💻This project helped me understand DOM manipulation and local storage.Features:✔ Add tasks✔ Delete tasks✔ Saves data automaticallyExcited to keep improving my JavaScript skills!#JavaScript #WebDevelopment #CodingJourney

#Day21 JavaScript just got a whole lot more interesting. Up until now, everything I wrote lived in the browser. Today I started working with Node.js and the fs module and for the first time, my code started talking to my computer directly. Three things clicked today: => Reading a file: "fs.readFile" opens a file sitting on your computer and prints its contents. That's it. No browser, no UI, just my code and my file system having a conversation. => Writing a file: "fs.writeFile" creates a brand new file and puts text inside it. If the file doesn't exist yet, Node creates it for you. One line of code does what used to feel like a whole process. => Appending to a file: "fs.appendFile" adds new content to an existing file without deleting what's already there. It runs after the file is created because in Node, async operations happen in sequence through callbacks. => process.on('uncaughtException'): Ending today with "process.on", this is a safety net. Instead of your program crashing with no explanation, it catches the error, tells you what went wrong, and shuts down cleanly. JavaScript isn't just a browser language. With Node.js, you can read files, write files, manage your system, and build backends all with the same language you already know. Same language. Bigger world. #NodeJS #JavaScript #M4ACELearningChallenge #BackendDevelopment #LearningToCode #WebDevelopment

Day 2/100 of JavaScript 🚀 Today’s Topic: "let", "const", "var", hoisting and TDZ. "var", "let", and "const" are used to declare variables, but they differ in scope and initialization behavior - "var" is function-scoped and during the creation phase it gets initialized with "undefined", so it can be accessed before assignment. - "let" and "const" are block-scoped and are registered in memory during creation, but not initialized immediately. This leads to TDZ (Temporal Dead Zone) a phase where the variable exists in memory but remains uninitialized and cannot be accessed. Accessing "let" or "const" variables before initialization results in a ReferenceError. - "const" must be initialized at declaration and cannot be reassigned. - "let" allows reassignment but not redeclaration in the same scope. These differences make "let" and "const" more predictable and safer compared to "var". #Day2 #JavaScript #100DaysOfCode