Run results for: UUID Generation (compatibility mode)

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:79.0) Gecko/20100101 Firefox/79.0

Browser: Firefox 79

Operating system: Windows

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
Jeff Ward v7	15188840.0 Ops/sec
Jon Surrell (not real UUID)	2126366.0 Ops/sec
Broofa (old)	349053.7 Ops/sec
My Test	574369.7 Ops/sec

Script Preparation code:


// Jeff Ward v7
var lut = []; for (var i=0; i<256; i++) { lut[i] = (i<16?'0':'')+(i).toString(16); }
function e7()
{
  var d0 = Math.random()*0xffffffff|0;
  var d1 = Math.random()*0xffffffff|0;
  var d2 = Math.random()*0xffffffff|0;
  var d3 = Math.random()*0xffffffff|0;
  return lut[d0&0xff]+lut[d0>>8&0xff]+lut[d0>>16&0xff]+lut[d0>>24&0xff]+'-'+
    lut[d1&0xff]+lut[d1>>8&0xff]+'-'+lut[d1>>16&0x0f|0x40]+lut[d1>>24&0xff]+'-'+
    lut[d2&0x3f|0x80]+lut[d2>>8&0xff]+'-'+lut[d2>>16&0xff]+lut[d2>>24&0xff]+
    lut[d3&0xff]+lut[d3>>8&0xff]+lut[d3>>16&0xff]+lut[d3>>24&0xff];
}

// Broofa (old)
function uuidv4_old() {
  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
    var r = Math.random() * 16 | 0, v = c == 'x' ? r : (r & 0x3 | 0x8);
    return v.toString(16);
  });
}


// Jon Surrell (not real UUID)
function guid() {
  function s4() {
    return Math.floor((1 + Math.random()) * 0x10000)
      .toString(16)
      .substring(1);
  }
  return s4() + s4() + '-' + s4() + '-' + s4() + '-' +
    s4() + '-' + s4() + s4() + s4();
}

// My Test
var UUID = (new function() {
  this._lut = []; for (var i = 0; i < 256; i++) {
    this._lut[i] = (i < 16 ? '0' : '') + (i).toString(16);
  };

  this._format = function (rarr) {
    return '' +
    this._lut[rarr[0]       & 0xff]        + this._lut[rarr[0] >>  8 & 0xff] + this._lut[rarr[0] >> 16 & 0xff] + this._lut[rarr[0] >> 24 & 0xff] + '-' +
    this._lut[rarr[1]       & 0xff]        + this._lut[rarr[1] >>  8 & 0xff] + '-' +
    this._lut[rarr[1] >> 16 & 0x0f | 0x40] + this._lut[rarr[1] >> 24 & 0xff] + '-' +
    this._lut[rarr[2]       & 0x3f | 0x80] + this._lut[rarr[2] >>  8 & 0xff] + '-' +
    this._lut[rarr[2] >> 16 & 0xff]        + this._lut[rarr[2] >> 24 & 0xff] +
    this._lut[rarr[3]       & 0xff]        + this._lut[rarr[3] >>  8 & 0xff] +
    this._lut[rarr[3] >> 16 & 0xff]        + this._lut[rarr[3] >> 24 & 0xff];
  };

  this._getRandomness = function () {
    if ('crypto' in window && 'Uint32Array' in window) {
      var dvals = new Uint32Array(4);
      window.crypto.getRandomValues(dvals);
      return dvals
    }
    return [
      Math.random() * 0x100000000 >>> 0,
      Math.random() * 0x100000000 >>> 0,
      Math.random() * 0x100000000 >>> 0,
      Math.random() * 0x100000000 >>> 0,
    ];
  };

  this.generate = function () {
    return this._format(this._getRandomness());
  };
}());

Tests:

Jeff Ward v7
e7();
Jon Surrell (not real UUID)
guid();
Broofa (old)
uuidv4_old();
My Test
UUID.generate();