universally unique identifier (UUID) functions: from Blob, from generator function, from mask

uuid-from-blob.js

// 13 June 2020
// Even better, modified from
// http://abhishekdutta.org/blog/standalone_uuid_generator_in_javascript.html

// 29 May 2022
// Even shorter

function uuid() {
  var url = URL.createObjectURL(new Blob());
  
  URL.revokeObjectURL(url);

  // remove prefix (e.g. blob:null/, blob:www.test.com/, ...)
  return url.substring(url.lastIndexOf("/") + 1);
}

/*
// June 2020 version:
function uuid() {
  var temp_url = URL.createObjectURL(new Blob());
  var uuid = temp_url.toString();

  URL.revokeObjectURL(temp_url);

  return uuid.substring(uuid.length - 36); // remove prefix (e.g. blob:null/, blob:www.test.com/, ...)
}*/


/* test it out */

var tests = Array.from(Array(10)).map((v,i) => uuid());
console.log(JSON.stringify(tests, null, 2));

/*
[
  "4079a4ea-ab95-4be0-90e4-b00b235a3832",
  "9117bb9a-8327-4e62-8959-1cb5205382ca",
  "185257f3-28d1-461a-97ec-a331f7be271b",
  "9392e5d5-ee7e-4546-98f0-6219dbced7f6",
  "2de94b6d-3aaf-4a95-849b-9a64c17de812",
  "fdcb5171-c860-43bc-b17d-23bc32041512",
  "56dfddec-bfb7-40cb-83e2-533d4538f22c",
  "592373fd-0f21-4e96-8242-8e50c70417a1",
  "f8c4bfb3-48e4-416f-9783-8561ce8a8ead",
  "a422d608-12f7-4ce5-b3af-6c0948137823"
]
 */

uuid-from-generator.js

// 27 July 2019
// UUID generator function 
// from https://codeburst.io/javascript-generator-yield-next-async-await-e428b0cb52e4

function* UUIDGenerator() {
    let d, r;
  
    while (true) {
        yield 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
          
            r = (Date.now() + Math.random() * 16) % 16 | 0;
            d = Math.floor(d / 16);
          
            return (c == 'x' ? r : (r & 0x3 | 0x8)).toString(16);
        });
    }
};

var UUID = UUIDGenerator();

var ids = Array(5).fill(0).map(x => {
  var uuid = UUID.next();
    
  console.log(uuid.value);
    
  return uuid.value;
});

console.log(ids);

/*
  [
    "87a8345b-5d1d-4428-bc9c-0744de22cfe8",
    "a36f392b-4ce0-4a59-ad7d-184e058e4ae9",
    "481c83ec-a63d-4e3b-9412-6fc2888f0ad7",
    "e2214233-c023-47d6-bb5c-f6f3f562b791",
    "829f61c3-d376-4817-bcae-b8dc353c4bdb"
  ]
*/

uuid-simplified.js

// 10 Feb 2020

// simplified, no generator*

// Generate a theoretically universally unique identifier.
function UUID() {
  return "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx".replace(/[xy]/g, function(c) {
    var r = (Date.now() + Math.random() * 16) % 16 | 0;

    return (c == "x" ? r : (r & 0x3) | 0x8).toString(16);
  });
}

var ids = Array(5).fill(0).map(x => {
  return UUID()
});

console.log(JSON.stringify(ids, null, 2));

/*
[
  "1f73aa19-d4a7-4f05-9a58-460be71358de",
  "5a967cd6-829d-48c1-ab58-f358aa9d554b",
  "d68f0dd1-dbb2-48f6-a76c-8f373dbeef16",
  "f35f2dd9-1444-4c1b-9e7d-f19ed489e444",
  "6054679f-cc79-411d-91ae-27589f950453"
]
*/