coolaj86/README.md

## README.md

      
    Raw
  

              README.md
            
          
    Now published as @root/uuid


Node version: https://github.com/therootcompany/uuid.js/blob/main/uuid.js
Browser version: https://github.com/therootcompany/uuid.js/blob/main/browser.js

This is started out as a curiosity, pasted as a gist but now, years later, I've come back to it because there are too many of these uuid modules out there and they're too complicated.
This, however, is easy to read and understand (for me, at least). Even its tests are dependncy and build-step free.
node-uuid vs crazy-uuid vs fast-uuid

Everybody knows about node-uuid and that it's pretty fast, right?
And everybody knows about 140byte-uuid and that it's insanely small, but really slow, right?
Well, while I was looking at all that math in node-uuid, I wondered to myself:
Is that really all that more efficient than just accessing strings?
(BTW, I was totally looking at the wrong function)
So I set out on a mission to make 'if' blocks and strings faster than bitwise operations, and I did! Over 2x faster! (generally in the range of 550,000/s instead of 250,000/s)
How is it 2x faster!?!?

Note that the huge time saver here is actually pooling crypto.randomBytes() ahead of time.
If we were to implement the same thing in node-uuid we might see an even bigger increase.
License

Copyright 2021 The Root Group, LLC 

Copyright 2015-2021 AJ ONeal
This Source Code Form is subject to the terms of the Mozilla 

Public License, v. 2.0. If a copy of the MPL was not distributed 

with this file, You can obtain one at https://mozilla.org/MPL/2.0/.

  
## fast-uuid.js
'use strict';

var crypto = require('crypto');
var pool = 31 * 128; // 36 chars minus 4 dashes and 1 four
var r = crypto.randomBytes(pool);
var j = 0;
var str = "10000000-1000-4000-8000-100000000000";
var len = str.length; // 36
var strs = [];

strs.length = len;
strs[8] = '-';
strs[13] = '-';
strs[18] = '-';
strs[23] = '-';

function uuid(){
  var ch;
  var chi;

  for (chi = 0; chi < len; chi++) {
    ch = str[chi];
    if ('-' === ch || '4' === ch) {
      strs[chi] = ch;
      continue;
    }

    // no idea why, but this is almost 4x slow if either
    // the increment is moved below or the >= is changed to >
    j++;
    if (j >= r.length) {
      r = crypto.randomBytes(pool);
      j = 0;
    }

    if ('8' === ch) {
      strs[chi] = (8 + r[j] % 4).toString(16);
      continue;
    }

    strs[chi] = (r[j] % 16).toString(16);
  }

  return strs.join('');
}

module.exports = { v4: uuid };

## test-uuid.js
'use strict';

var uuid = require('./fast-uuid');
// var uuid = require('node-uuid');
var now = Date.now();
var t = 0;
var msec;

for (t; t < 100000; t++) {
  uuid.v4();
}

msec = Date.now() - now;
console.log(Math.floor((1000 / msec) * 100000) + ' uuid/s');
console.log('100000 in ' + (Date.now() - now) + 'ms');
console.log(uuid.v4());
	'use strict';

	var crypto = require('crypto');
	var pool = 31 * 128; // 36 chars minus 4 dashes and 1 four
	var r = crypto.randomBytes(pool);
	var j = 0;
	var str = "10000000-1000-4000-8000-100000000000";
	var len = str.length; // 36
	var strs = [];

	strs.length = len;
	strs[8] = '-';
	strs[13] = '-';
	strs[18] = '-';
	strs[23] = '-';

	function uuid(){
	var ch;
	var chi;

	for (chi = 0; chi < len; chi++) {
	ch = str[chi];
	if ('-' === ch \|\| '4' === ch) {
	strs[chi] = ch;
	continue;
	}

	// no idea why, but this is almost 4x slow if either
	// the increment is moved below or the >= is changed to >
	j++;
	if (j >= r.length) {
	r = crypto.randomBytes(pool);
	j = 0;
	}

	if ('8' === ch) {
	strs[chi] = (8 + r[j] % 4).toString(16);
	continue;
	}

	strs[chi] = (r[j] % 16).toString(16);
	}

	return strs.join('');
	}

	module.exports = { v4: uuid };
	'use strict';

	var uuid = require('./fast-uuid');
	// var uuid = require('node-uuid');
	var now = Date.now();
	var t = 0;
	var msec;

	for (t; t < 100000; t++) {
	uuid.v4();
	}

	msec = Date.now() - now;
	console.log(Math.floor((1000 / msec) * 100000) + ' uuid/s');
	console.log('100000 in ' + (Date.now() - now) + 'ms');
	console.log(uuid.v4());