@efflore/ui-element/test/util/pseudo-random.js

UIElement - minimal reactive framework based on Web Components

export function pseudoRandom(seed = "seed") {
  const hash = xmur3a(seed);
  const rng = sfc32(hash(), hash(), hash(), hash());
  return rng;
}
/* these are adapted from https://github.com/bryc/code/blob/master/jshash/PRNGs.md
 * (License: Public domain) */
/** random number generator originally in PractRand */
function sfc32(a, b, c, d) {
  return function () {
    a >>>= 0;
    b >>>= 0;
    c >>>= 0;
    d >>>= 0;
    let t = (a + b) | 0;
    a = b ^ (b >>> 9);
    b = (c + (c << 3)) | 0;
    c = (c << 21) | (c >>> 11);
    d = (d + 1) | 0;
    t = (t + d) | 0;
    c = (c + t) | 0;
    return (t >>> 0) / 4294967296;
  };
}
/** MurmurHash3 */
export function xmur3a(str) {
  let h = 2166136261 >>> 0;
  for (let k, i = 0; i < str.length; i++) {
    k = Math.imul(str.charCodeAt(i), 3432918353);
    k = (k << 15) | (k >>> 17);
    h ^= Math.imul(k, 461845907);
    h = (h << 13) | (h >>> 19);
    h = (Math.imul(h, 5) + 3864292196) | 0;
  }
  h ^= str.length;
  return function () {
    h ^= h >>> 16;
    h = Math.imul(h, 2246822507);
    h ^= h >>> 13;
    h = Math.imul(h, 3266489909);
    h ^= h >>> 16;
    return h >>> 0;
  };
}