@woosh/meep-engine/src/core/math/random/roundFair.js

Pure JavaScript game engine. Fully featured and production ready.

/**
 * Performs a probabilistic rounding where a fraction is rounded up or down with probability equal to the fraction
 * @param {number} number
 * @param {function} random
 * @returns {int}
 */
export function roundFair(number, random) {

    const mantissa = number % 1;
    const roll = random();

    if (roll > mantissa) {
        return Math.floor(number);
    } else {
        return Math.ceil(number);
    }

}