只是另一个更可读的变量,只有两个突变。

function uuid4()
{
  function hex (s, b)
  {
    return s +
      (b >>> 4   ).toString (16) +  // high nibble
      (b & 0b1111).toString (16);   // low nibble
  }

  let r = crypto.getRandomValues (new Uint8Array (16));

  r[6] = r[6] >>> 4 | 0b01000000; // Set type 4: 0100
  r[8] = r[8] >>> 3 | 0b10000000; // Set variant: 100

  return r.slice ( 0,  4).reduce (hex, '' ) +
         r.slice ( 4,  6).reduce (hex, '-') +
         r.slice ( 6,  8).reduce (hex, '-') +
         r.slice ( 8, 10).reduce (hex, '-') +
         r.slice (10, 16).reduce (hex, '-');
}

我想了解布罗法的答案,所以我扩展了它并添加了评论:

var uuid = function () {
    return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(
        /[xy]/g,
        function (match) {
            /*
            * Create a random nibble. The two clever bits of this code:
            *
            * - Bitwise operations will truncate floating point numbers
            * - For a bitwise OR of any x, x | 0 = x
            *
            * So:
            *
            * Math.random * 16
            *
            * creates a random floating point number
            * between 0 (inclusive) and 16 (exclusive) and
            *
            * | 0
            *
            * truncates the floating point number into an integer.
            */
            var randomNibble = Math.random() * 16 | 0;

            /*
            * Resolves the variant field. If the variant field (delineated
            * as y in the initial string) is matched, the nibble must
            * match the mask (where x is a do-not-care bit):
            *
            * 10xx
            *
            * This is achieved by performing the following operations in
            * sequence (where x is an intermediate result):
            *
            * - x & 0x3, which is equivalent to x % 3
            * - x | 0x8, which is equivalent to x + 8
            *
            * This results in a nibble between 8 inclusive and 11 exclusive,
            * (or 1000 and 1011 in binary), all of which satisfy the variant
            * field mask above.
            */
            var nibble = (match == 'y') ?
                (randomNibble & 0x3 | 0x8) :
                randomNibble;

            /*
            * Ensure the nibble integer is encoded as base 16 (hexadecimal).
            */
            return nibble.toString(16);
        }
    );
};

function randomHex(length) {
    var random_string = '';
    if(!length){
        length = 1;
    }
    for(var i=0; i<length; i+=1){
        random_string += Math.floor(Math.random() * 15).toString(16);
    }
    return random_string;
}

function guid() {
    return randomHex(8);
}

这里是一个完全不符合但非常有效的实施,以产生一个ASCII安全的GUID类似的独特识别器。

function generateQuickGuid() {
    return Math.random().toString(36).substring(2, 15) +
        Math.random().toString(36).substring(2, 15);
}

创建 26 个字符 [a-z0-9],产生一个 UID 既较短又比 RFC 符合的 GUID 更独特。

这里是这个功能的使用例子和时间表,以及这个问题的其他几个答案。

>>> generateQuickGuid()
"nvcjf1hs7tf8yyk4lmlijqkuo9"
"yq6gipxqta4kui8z05tgh9qeel"
"36dh5sec7zdj90sk2rx7pjswi2"
runtime: 32.5s

>>> GUID() // John Millikin
"7a342ca2-e79f-528e-6302-8f901b0b6888"
runtime: 57.8s

>>> regexGuid() // broofa
"396e0c46-09e4-4b19-97db-bd423774a4b3"
runtime: 91.2s

>>> createUUID() // Kevin Hakanson
"403aa1ab-9f70-44ec-bc08-5d5ac56bd8a5"
runtime: 65.9s

>>> UUIDv4() // Jed Schmidt
"f4d7d31f-fa83-431a-b30c-3e6cc37cc6ee"
runtime: 282.4s

>>> Math.uuid() // broofa
"5BD52F55-E68F-40FC-93C2-90EE069CE545"
runtime: 225.8s

>>> Math.uuidFast() // broofa
"6CB97A68-23A2-473E-B75B-11263781BBE6"
runtime: 92.0s

>>> Math.uuidCompact() // broofa
"3d7b7a06-0a67-4b67-825c-e5c43ff8c1e8"
runtime: 229.0s

>>> bitwiseGUID() // jablko
"baeaa2f-7587-4ff1-af23-eeab3e92"
runtime: 79.6s

>>>> betterWayGUID() // Andrea Turri
"383585b0-9753-498d-99c3-416582e9662c"
runtime: 60.0s

>>>> UUID() // John Fowler
"855f997b-4369-4cdb-b7c9-7142ceaf39e8"
runtime: 62.2s

这里是时间代码。

var r;
console.time('t'); 
for (var i = 0; i < 10000000; i++) { 
    r = FuncToTest(); 
};
console.timeEnd('t');

const uuid = url => url.substr(-36);

上述将与创建ObjectURL的任何合适的实施工作,因为规格明确要求 UUID 添加到前者返回的 URL 的结尾。

要清楚,有时 - 点击,也许大部分时间,所有考虑 - 你想生成一个 UUID 别的东西,而不是资源,你创建的 URL 与创建ObjectURL. 在这些情况下,呼叫后一个方法在一些新的 Blob() 将绝对坦克的性能(和泄漏的记忆,除非你清理后自己使用相应的 revokeObjectURL)。

我不建议您使用上述方法仅为创建UUID,除非您已经通过创建ObjectURL获得的URL或最终具有UUID的东西。

我只是想提到上述版本的完整性。

基于加密 API 的 2017-06-28 的 Broofa 的 TypeScript 版本:

function genUUID() {
    // Reference: https://stackoverflow.com/a/2117523/709884
    return ("10000000-1000-4000-8000-100000000000").replace(/[018]/g, s => {
        const c = Number.parseInt(s, 10)
        return (c ^ crypto.getRandomValues(new Uint8Array(1))[0] & 15 >> c / 4).toString(16)
    })
}

原因:

使用 + 之间的数字( )和数字不有效 从行到数字的转换必须是明确的