JavaScript Guide

Introduction

JavaScript is a versatile, high‑level programming language that powers interactive behavior on the web. This guide covers fundamentals, modern features, and hands‑on examples.

Table of Contents

• Basics
• Functions
• DOM Manipulation
• Async / Await
• Playground

Basics

Declare variables using let, const, or var. Use === for strict equality.

let message = "Hello, World!";
if (message === "Hello, World!") {
    console.log(message);
}

Functions

Arrow functions provide a concise syntax:

const add = (a, b) => a + b;
console.log(add(2, 3)); // 5

DOM Manipulation

Interact with page elements via document.querySelector and event listeners.

document.querySelector('#myBtn').addEventListener('click', () => {
    alert('Button clicked!');
});

Async / Await

Handle asynchronous operations cleanly with async functions.

async function fetchData() {
    const response = await fetch('https://api.example.com/data');
    const data = await response.json();
    console.log(data);
}
fetchData();

Playground

Write JavaScript code below and see the result instantly.