The Math Object

The JavaScript Math Object

The built-in Math object is a namespace containing mathematical constants and functions. Unlike most JavaScript objects, you never instantiate it — all properties and methods are accessed directly on Math. It provides everything from basic rounding to trigonometry and logarithms.

Rounding Methods

Math.round(x) rounds to the nearest integer (0.5 rounds up). Math.floor(x) always rounds down toward negative infinity. Math.ceil(x) always rounds up toward positive infinity. Math.trunc(x) removes the decimal part without rounding.

Math.random()

Math.random() returns a pseudo-random float in the range [0, 1). To generate a random integer between min and max (inclusive), use the formula Math.floor(Math.random() * (max - min + 1)) + min.

Other Useful Methods

Math.abs(x) — absolute value
Math.max(...values) and Math.min(...values) — largest/smallest
Math.pow(base, exp) — exponentiation (prefer the ** operator)
Math.sqrt(x) — square root

Example

console.log(Math.round(4.5));  // 5
console.log(Math.round(4.4));  // 4
console.log(Math.floor(4.9));  // 4
console.log(Math.ceil(4.1));   // 5
console.log(Math.trunc(-4.9)); // -4
console.log(Math.abs(-7));     // 7
console.log(Math.max(1, 5, 3, 9, 2)); // 9
console.log(Math.min(1, 5, 3, 9, 2)); // 1
console.log(Math.sqrt(16));    // 4
console.log(Math.PI);          // 3.141592653589793
const rand = Math.floor(Math.random() * 6) + 1;
console.log(rand); // random 1-6

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Pro Tip

Use Math.floor(Math.random() * n) to get a random integer from 0 to n-1. Add a minimum value to shift the range — this is the standard dice-roll pattern in JavaScript.

Related Resources

JavaScript Reference

Complete tag & property list

JavaScript How-To Guides

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JavaScript Exercises

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