js生成uuid的方法

- 日理万妓 2022-08-21 00:13 185阅读 0赞

找到三种生成uuid方法，如下：

/*!
    Math.uuid.js (v1.4)
    
    http://www.broofa.com
    
    mailto:robert@broofa.com
    
    Copyright (c) 2010 Robert Kieffer
    Dual licensed under the MIT and GPL licenses.
    */
    
    /*
     * Generate a random uuid.
     *
     * USAGE: Math.uuid(length, radix)
     *   length - the desired number of characters
     *   radix  - the number of allowable values for each character.
     *
     * EXAMPLES:
     *   // No arguments  - returns RFC4122, version 4 ID
     *   >>> Math.uuid()
     *   "92329D39-6F5C-4520-ABFC-AAB64544E172"
     *
     *   // One argument - returns ID of the specified length
     *   >>> Math.uuid(15)     // 15 character ID (default base=62)
     *   "VcydxgltxrVZSTV"
     *
     *   // Two arguments - returns ID of the specified length, and radix. (Radix must be <= 62)
     *   >>> Math.uuid(8, 2)  // 8 character ID (base=2)
     *   "01001010"
     *   >>> Math.uuid(8, 10) // 8 character ID (base=10)
     *   "47473046"
     *   >>> Math.uuid(8, 16) // 8 character ID (base=16)
     *   "098F4D35"
     */
    (function() {
      // Private array of chars to use
      var CHARS = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'.split('');
    
      Math.uuid = function (len, radix) {
        var chars = CHARS, uuid = [], i;
        radix = radix || chars.length;
    
        if (len) {
          // Compact form
          for (i = 0; i < len; i++) uuid[i] = chars[0 | Math.random()*radix];
        } else {
          // rfc4122, version 4 form
          var r;
    
          // rfc4122 requires these characters
          uuid[8] = uuid[13] = uuid[18] = uuid[23] = '-';
          uuid[14] = '4';
    
          // Fill in random data.  At i==19 set the high bits of clock sequence as
          // per rfc4122, sec. 4.1.5
          for (i = 0; i < 36; i++) {
            if (!uuid[i]) {
              r = 0 | Math.random()*16;
              uuid[i] = chars[(i == 19) ? (r & 0x3) | 0x8 : r];
            }
          }
        }
    
        return uuid.join('');
      };
    
      // A more performant, but slightly bulkier, RFC4122v4 solution.  We boost performance
      // by minimizing calls to random()
      Math.uuidFast = function() {
        var chars = CHARS, uuid = new Array(36), rnd=0, r;
        for (var i = 0; i < 36; i++) {
          if (i==8 || i==13 ||  i==18 || i==23) {
            uuid[i] = '-';
          } else if (i==14) {
            uuid[i] = '4';
          } else {
            if (rnd <= 0x02) rnd = 0x2000000 + (Math.random()*0x1000000)|0;
            r = rnd & 0xf;
            rnd = rnd >> 4;
            uuid[i] = chars[(i == 19) ? (r & 0x3) | 0x8 : r];
          }
        }
        return uuid.join('');
      };
    
      // A more compact, but less performant, RFC4122v4 solution:
      Math.uuidCompact = function() {
        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);
        });
      };
    })();

使用uuidFast效率更高些。来源于：http://www.cnblogs.com/greengnn/archive/2011/10/06/2199719.html

2014年08月04日 再增加一种方法，源于backbone.localStorage.js，胜在代码量够少：

// Generate four random hex digits.
    function S4() {
       return (((1+Math.random())*0x10000)|0).toString(16).substring(1);
    };
    // Generate a pseudo-GUID by concatenating random hexadecimal.
    function guid() {
       return (S4()+S4()+"-"+S4()+"-"+S4()+"-"+S4()+"-"+S4()+S4()+S4());
    };

加个简介（源自https://zh.wikipedia.org/zh-cn/全局唯一标识符）：   
全局唯一标识符，简称GUID（发音为 /ˈɡuːɪd/或/ˈɡwɪd/），是一种由算法生成的唯一标识，通常表示成32个16进制数字（0－9，A－F）组成的字符串，如：\{21EC2020-3AEA-1069-A2DD-08002B30309D\}，它实质上是一个128位长的二进制整数。GUID一词有时也专指微软对UUID标准的实现。

GUID的主要目的是产生完全唯一的数字。在理想情况下，任何计算机和计算机集群都不会生成两个相同的GUID。GUID的总数也足够大，达到了2128（3.4×1038）个，所以随机生成两个相同GUID的可能性是非常小的，但并不为0。所以，用于生成GUID的算法通常都加入了非随机的参数（如时间），以保证这种重复的情况不会发生。