🌟 *JavaScript Fundamentals – From Basics to Advanced (Beginner-Friendly)* 🟢 *1. JavaScript Basics* - *Variables:* Use `let`, `const` (block-scoped), avoid `var` (function-scoped). ```js const name = "John"; let age = 25; ``` - *Data Types:* String, Number, Boolean, Undefined, Null, Object, Array - *Operators:* Arithmetic (+, -, *), Comparison (==, ===, >, <), Logical (&&, ||, !) - *Functions:* Named & Arrow functions ```js function greet() { return "Hi"; } const greet = () => "Hi"; ``` - *Loops & Conditions:* `if-else`, `for`, `while`, `forEach` 🟡 *2. DOM Manipulation* - *Selectors:* `getElementById`, `querySelector`, etc. - *Events:* `onclick`, `addEventListener` - *Changing HTML/CSS:* `innerText`, `style`, `classList` 🟡 *3. ES6+ Features* - *Destructuring:* ```js const [a, b] = [1, 2]; const {name} = {name: "Alice"}; ``` - *Spread/Rest:* ```js const arr = [...oldArr]; function sum(...nums) {} ``` - *Template Literals:* ```js `Hello, ${name}` ``` - *Arrow Functions, Default Params, Optional Chaining* 🟡 *4. Async JavaScript* - *Callbacks → Promises → Async/Await* ```js async function getData() { const res = await fetch(url); const data = await res.json(); } ``` 🟡 *5. Array Methods* - `.map()`, `.filter()`, `.reduce()`, `.forEach()` — powerful for clean coding 🔵 *6. Error Handling* - `try...catch` blocks - Custom error messages 🔵 *7. Local Storage / Session Storage* - Save key-value data in browser ```js localStorage.setItem("token", "abc123"); ``` 🔵 *8. JSON & APIs* - `fetch()` data from API - Work with JSON using `.json()` method 🔥 *Tip:* Build mini apps like calculator, to-do list, or quiz app to master these skills. *React ❤️ for more!*