Generate a random boolean

Return true or false with equal probability.

JavaScriptNode.js & browsers Version 1.0.0 · MIT · .md

function randomBoolean() { return Math.random() < 0.5; }

Usage

const flips = Array.from({ length: 1000 }, randomBoolean);
flips.every(value => typeof value === 'boolean'); // → true
new Set(flips).size; // → 2

Lines marked → were executed in Node.js 22 and in headless Chromium, and each result was compared with the value shown. Lines marked e.g. are illustrative.

Know the limits

• Math.random returns [0, 1), so < 0.5 splits it into two equal halves.
• Not for security decisions; use crypto.getRandomValues.

The function above is the code the usage lines run. It does not validate its arguments; add checks where it receives untrusted input.

Keep exploring

• Generate a random floating point number in given range — Scale Math.random into [min, max).
• Generate a random hex color — Return a #rrggbb color from 24 random bits.
• Generate a random integer in given range — Return an integer from min to max, both included.