meteor/packages/random/createAleaGenerator.js

import AleaRandomGenerator from './AleaRandomGenerator';

// instantiate RNG.  Heuristically collect entropy from various sources when a
// cryptographic PRNG isn't available.

// client sources
const height = (typeof window !== 'undefined' && window.innerHeight) ||
      (typeof document !== 'undefined'
       && document.documentElement
       && document.documentElement.clientHeight) ||
      (typeof document !== 'undefined'
       && document.body
       && document.body.clientHeight) ||
      1;

const width = (typeof window !== 'undefined' && window.innerWidth) ||
      (typeof document !== 'undefined'
       && document.documentElement
       && document.documentElement.clientWidth) ||
      (typeof document !== 'undefined'
       && document.body
       && document.body.clientWidth) ||
      1;

const agent = (typeof navigator !== 'undefined' && navigator.userAgent) || '';

export default function createAleaGenerator() {
  return new AleaRandomGenerator({
    seeds: [new Date, height, width, agent, Math.random()],
  });
}