Number (integers, floats, NaN, Infinity)

The number type represents both integers and floating‑point numbers.

let integer = 42;
let float = 3.14;
let negative = -10;
let scientific = 2.5e3; // 2500

Special numeric values:

NaN (Not‑a‑Number): result of an invalid or undefined mathematical operation.

let result = "hello" * 5; // NaN
console.log(isNaN(result)); // true

Infinity and -Infinity: represent mathematical infinity.

let tooBig = 1 / 0; // Infinity
let tooSmall = -1 / 0; // -Infinity

Number methods:

Number.isInteger(), Number.isNaN(), Number.parseFloat(), Number.parseInt().

console.log(Number.isInteger(42)); // true
console.log(Number.parseInt("123px")); // 123

Precision issues: Floating point arithmetic is not always exact.

console.log(0.1 + 0.2); // 0.30000000000000004

Use toFixed() or libraries for exact decimal calculations.