generateId = () => {
  var uuid = '';
  for (var i = 0; i < 32; i++) {
    var random = (Math.random() * 16) | 0; // eslint-disable-line

    if (i === 8 || i === 12 || i === 16 || i === 20) {
      uuid += '-';
    }
    uuid += (i === 12 ? 4 : i === 16 ? (random & 3) | 8 : random).toString(16); // eslint-disable-line
  }
  return uuid;
}
UUID v4 generator
https://gist.github.com/jcxplorer/823878
@returns {string}