@amarillion/helixgraph/lib/random.js

A collection of graph algorithms for game development

/**
 * Pick a random number between `0` (inclusive) and `n` (exclusive).
 * In other words, pick a non-negative number below `n`.
 */
export const randomInt = (n, prng = Math.random) => Math.floor(prng() * n);
/**
 * Randomly pick one item from an array of items.
 */
export const pickOne = (array, prng = Math.random) => array[randomInt(array.length, prng)];
/**
Knuth-Fisher-Yates shuffle algorithm.

Array is shuffled in-place.
Reference to array is returned.
*/
export function shuffle(array, prng = Math.random) {
    const len = array.length;
    for (let i = len - 1; i > 0; i--) {
        const n = randomInt(i + 1, prng);
        [array[n], array[i]] = [array[i], array[n]];
    }
    return array;
}