Conditions with if and else

Conditions choose which block runs based on a boolean expression. Keep conditions readable and use strict comparisons where possible.

Loops: for and while

Loops repeat work. A for loop suits a known number of iterations, while a while loop runs as long as its condition remains true.

Introduction to JavaScript

JavaScript adds behavior to websites. It can respond to clicks, update page content, validate inputs, and communicate with servers.

Using the Browser Console

The developer console helps inspect values and debug code. console.log() prints information, while console.error() highlights errors.

Variables: let and const

Use const when a variable binding should not be reassigned and let when reassignment is needed. Avoid var in modern beginner code.

Data Types

Common types include string, number, boolean, undefined, null, object, and bigint. typeof can inspect most types, but typeof null is a historical quirk.

Operators and Expressions

Arithmetic operators calculate values; comparison operators compare them. Prefer === and !== to avoid implicit type conversion surprises.

Strings and Template Literals

Strings hold text. Template literals use backticks and ${} expressions to combine values into readable messages.