Topic 01 / 15

Introduction to JavaScript & Setup

~7 min read // JavaScript Series // Coding India

The Language of the Web

JavaScript is the only language browsers execute natively — every interactive website you’ve ever used runs it. Since Node.js, it also runs servers, build tools, and CLIs. One language, full stack: that’s why JS has been the world’s most-used language for over a decade.

Where to Run It

1. The browser console — press F12, open the Console tab, and type:

2 + 2                          // 4
console.log("Coding India")    // prints to the console

2. A script in a page — create two files:

<!-- index.html -->
<!DOCTYPE html>
<html>
<head><title>JS Lab</title></head>
<body>
  <h1 id="title">Hello</h1>
  <script src="app.js"></script>   <!-- bottom of body -->
</body>
</html>

// app.js
console.log("script loaded");
document.getElementById("title").textContent = "Hello from JS";

3. Node.js — install from nodejs.org and run files directly:

node app.js

Statements & Comments

// single-line comment
/* multi-line
   comment */
let x = 5;        // semicolons are technically optional —
let y = 10;       // but use them; it avoids rare parsing surprises

Strict Mode & Modern JS

This series teaches modern JavaScript (ES6+): let/const, arrow functions, template literals, modules, async/await. You’ll still see pre-2015 code in the wild (var, function callbacks everywhere) — we’ll flag the old patterns so you can read them, but you’ll write the new ones.

console Is Your Best Friend

console.log("value:", x);
console.warn("careful");
console.error("something broke");
console.table([{name: "Ravi", score: 82}, {name: "Asha", score: 99}]);