Beginner JavaScript Notes 2025 📘

Welcome to Beginner JavaScript Notes 2025!
This repository is created for absolute beginners who want to learn JavaScript in NodeJS environment step by step with simple examples, explanations, and notes.

---

📌 What is Inside?

• Clear explanations of JavaScript concepts using NodeJS environment in beginner-friendly language.
• Code snippets with comments to understand how things work.
• Theory notes + Practical examples (both included for clarity).
• Covers basics like:
  • Variables (var, let, const)
  • Datatype (Primitive & Non-primitive)
  • Operators (Arithmetic, Assignment, Logical, Comparison, Bitwise etc)
  • Stack & Heap
  • String
  • Number & Maths
  • Date & Time
  • Arrays & Objects
  • Functions (Normal vs Arrow Functions)
  • Scope & Hoisting
  • Immediately Invoked Function Expressions (IIFE)
  • Function Execution Context & Call Stack
  • Control Flow (if-else, switch)
  • Loops & Conditionals (for, while, do-while)
  • For (forof, forin, foreach)
  • Filter, Map, Reduce
  • Document Object Model (DOM) =>
  • DOM: getElementById, getElementByClassName, getElementByName, getElementByTagName
  • DOM: querySelector, querySelectorAll
  • DOM: innerText, innerHTML, textContent
  • DOM: HTMLCollection, NodeList
  • DOM: ParentToChild & ChildToParent Traversing, NextElementSibling, NodeList
  • DOM: How To Create (createElement), Edit & Delete Element
  • Events: addEventListener, Event propagation(capturing & bubbling)
  • Events: SetTimeout, clearTimeout, setInterval, clearInterval
  • XMLHttpRequest: open(), send(), readyState, onreadystatechange
  • v8 Engine: https://github.com/v8/v8
  • Promise: resolve, reject, then catch finally, async await, try catch, fetch
  • Object Literals
  • Constructor Function
  • OOP: Abstraction, Polymorphism, Encapsulation, Inheritance
  • Prototype: Prototypal inheritance, new, this
  • Class Constructor, Inheritance, Static property
  • Call, Bind & Apply
  • Advance Objects:getOwnPropertyDescriptor, defineProperty
  • Getter & Setter: class, function, object use-cases
  • Lexical Scoping & Closure
  • Projects:
  1. Color Changer
  2. BMI Generator
  3. Digital Clock
  4. Guess The Number
  5. Unlimited Colors
  6. Keyboard Check

---

🧑‍🎓 Who is this for?

• Complete beginners in JavaScript on NodeJS Environment.
• Students who want easy-to-understand notes.
• Anyone who prefers short & clear examples instead of reading long documentation.

---

🚀 How to Use

1. Clone this repo or download the files.
2. Go through each file step by step.
3. Run examples in browser console or with Node.js.
4. Read comments in the code (they act like mini-notes ✍️).
5. Flow Diagram explanation using Draw.io.

---

📝 Example Snippet

// Normal Function
function greet(name) {
  return `Hello, ${name}!`;
}

// Arrow Function
const greetArrow = (name) => `Hello, ${name}!`;

console.log(greet("Sayan"));       // Output: Hello, Sayan!
console.log(greetArrow("World"));  // Output: Hello, World!