Dummy data + Flood storage

dd.js

/**
 * dd (aka dummy data)
 * -------------------
 *  
 * Generate dummy data in the form of a String
 *
 * @param {object} options
 * @param {number} [options.sizeInKB=0] - the size of the String in KB, if specified `sizeInMB` is ignored
 * @param {number} [options.sizeInMB=1] - the size of the String in MB
 * @returns {string} a random string of the specified size
 */
function dd({sizeInKB = 0, sizeInMB = 1} = {}) {
  const create1KBChunk = () => {
    const dec2hex = dec => `0${dec.toString(16)}`.substr(-2);
    const data = new Uint8Array(512)
    crypto.getRandomValues(data);
    return Array.from(data, dec2hex).join('');
  }
  const numOfChunks = sizeInKB || sizeInMB * 1024;
  return new Uint8Array(numOfChunks).reduce(str => str + create1KBChunk(), '');
}

flood.js

/**
 * Flood your storage with data until you get QuotaExceeded DOMException
 *
 * Results in a full storage that can't store more data with KB precision.
 *
 * If you know the browser's storage limit, set `startWithInKB` a bit lower
 * to get a full storage faster.
 *
 * @param options
 * @param {Storage} [options.storage=sessionStorage] - the storage to flood
 * @param {number} [options.startWithInKB=4500] - the data in KB to start with
 */
function flood({storage = localStorage, startWithInKB = 4500} = {}) {
  const numberFormat = new Intl.NumberFormat();
  let step = 250;
  const tryToFlood = (inc = 0) => {
    const data = dd({sizeInKB: startWithInKB + inc});
    console.log(`Flooding storage with ${numberFormat.format(data.length)} bytes`);
    try {
      storage.setItem('dummy', data);
    } catch (err) {
      if (step === 1) {
        throw err;
      }
      inc = inc - step;
      step = Math.ceil(step / 2);
    }
    requestIdleCallback(() => tryToFlood(inc + step));
  };
  tryToFlood();
}