Math Object: round, floor, ceil, abs, max, min, pow, sqrt

Syntax

Math.round(num)
Math.floor(num)
Math.max(...nums)

Examples

console.log(Math.round(4.5));  // 5 - rounds to nearest, ties round up
console.log(Math.round(4.4));  // 4
console.log(Math.floor(4.9));  // 4 - always rounds down
console.log(Math.ceil(4.1));   // 5 - always rounds up
console.log(Math.trunc(4.9));  // 4 - simply removes the decimal part
console.log(Math.trunc(-4.9)); // -4 - different from floor for negatives

console.log(Math.abs(-5));       // 5
console.log(Math.max(3, 7, 2));  // 7
console.log(Math.min(3, 7, 2));  // 2

// Finding max/min in an array requires spread
const numbers = [4, 8, 2, 9, 1];
console.log(Math.max(...numbers)); // 9

console.log(Math.pow(2, 3));  // 8 - same as 2 ** 3
console.log(2 ** 3);           // 8 - the ** operator is now preferred
console.log(Math.sqrt(16));    // 4
console.log(Math.cbrt(27));    // 3 - cube root

Best practices

• Use the ** exponentiation operator instead of Math.pow() in modern code - it is more concise for the common case
• Choose the right rounding method deliberately - round() for nearest, floor()/ceil() when you specifically need to always round down/up
• Use Math.max(...array) with spread syntax to find the largest value in an array, since Math.max() itself takes individual arguments
• Remember Math methods are all static - always call them as Math.round(), never new Math().round()

At a glance

Purpose

Application logic and interaction

File extension

.js · .mjs

Runs in

Browsers and JavaScript runtimes

Usually used with

HTML, CSS and Web APIs

Specifications & further reading

• ECMAScript specification

Related JavaScript documentation