Hello World

JavaScript · Reference cheat sheet

📋 Overview

Hello World confirms your JS environment works. The usual first call is console.log, which writes to the browser console or the terminal (Node).

Piece	Role
`console.log(...)`	Print values for humans / debugging
String literal	`"text"` or `'text'` or `text`
Statement	An instruction, often ending with `;` (ASI may insert them)
Script	Code loaded by Node or a browser

Semicolons are recommended for beginners even though Automatic Semicolon Insertion exists.

Node script:

console.log("Hello, World!");

node hello.js

Multiple values:

const name = "Ada";
console.log("Hello,", name);
console.log(`Hello, ${name}!`);

Browser alert (UI, not for real apps):

alert("Hello, World!");

Log different types:

console.log(42);
console.log(true);
console.log({ ok: true });
console.log(["a", "b"]);

In the browser, look at the Console tab — not the page body — for console.log.
alert blocks the UI; use it sparingly while learning.
Smart quotes from documents break string literals.
Running TypeScript (.ts) needs a toolchain; plain Hello World should be .js.