JavaScript Basics

JavaScript brings your pages to life. It runs in the browser and can change anything on the page after it loads.

Variables with let and const

Variables store values. Use const for values that never change and let for ones that do.

const title = "hackweb.dev";
let score = 0;
score = score + 10;
console.log(title, score);

Values and types

JavaScript has a few core types — numbers, strings, booleans, and more.

const age = 25;          // number
const name = "Ada";      // string
const isAdmin = true;    // boolean
console.log(typeof age, typeof name, typeof isAdmin);

Strings

Strings are text. Join them with + or with template literals.

const first = "Ada";
const last = "Lovelace";
const full = `${first} ${last}`;
console.log(full);

console.log

console.log prints values to the console — your best debugging friend.

console.log("hello from the console");

The event loop

JavaScript handles one thing at a time, but things like timers happen in the background. The event loop is how they come back. Watch it in action:

name="event-loop"