JavaScript variables can hold many kinds of values. Mastering primitive types (number, string, boolean), reference types (objects, arrays), and type coercion is essential. Understanding the distinction between mutable and immutable values is critical for avoiding bugs.

JavaScript has two main categories of values:

Use the right keyword for the job:

• const — value won't be reassigned
• let — value may change
• var — older, function-scoped; prefer const or let

const greeting = 'Hello';
let count = 42;
var active = true;

const person = { name: 'Alice', age: 30 };
const numbers = [1, 2, 3, 4, 5];
// ...

In the editor, declare variables for different data types and log their typeof values.

JavaScript variables can hold many kinds of values. Mastering primitive types (number, string, boolean), reference types (objects, arrays), and type coercion is essential. Understanding the distinction between mutable and immutable values is critical for avoiding bugs.

JavaScript has two main categories of values:

Use the right keyword for the job:

• const — value won't be reassigned
• let — value may change
• var — older, function-scoped; prefer const or let

const greeting = 'Hello';
let count = 42;
var active = true;

const person = { name: 'Alice', age: 30 };
const numbers = [1, 2, 3, 4, 5];
// ...

In the editor, declare variables for different data types and log their typeof values.