全局唯一标识符（GUID，Globally Unique Identifier）也称作UUID(Universally Unique IDentifier) 。GUID是一种由算法生成的二进制长度为128位的数字标识符。GUID 的格式为“xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx”，其中的 x 是 0-9 或 a-f 范围内的一个32位十六进制数。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 的总数达到了2128（3.4×1038）个，所以随机生成两个相同GUID的可能性非常小，但并不为0。GUID一词有时也专指微软对UUID标准的实现。
算法一 function uuid() { let s = []; let hexDigits = "0123456789abcdef"; for (let i = 0; i < 36; i++) { s[i] = hexDigits.substr(Math.floor(Math.random() * 0x10), 1); } s[14] = "4"; // bits 12-15 of the time_hi_and_version field to 0010 s[19] = hexDigits.substr((s[19] & 0x3) | 0x8, 1); // bits 6-7 of the clock_seq_hi_and_reserved to 01 s[8] = s[13] = s[18] = s[23] = "-"; let uuid = s.join(""); return uuid;} 算法二 function guid() { return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) { let r = Math.random()*16|0, v = c == 'x' ? r : (r&0x3|0x8); return v.toString(16); });} 算法三 function guid() { function S4() { return (((1+Math.random())*0x10000)|0).toString(16).substring(1); } return (S4()+S4()+"-"+S4()+"-"+S4()+"-"+S4()+"-"+S4()+S4()+S4());} 算法四 function uuid(len, radix) { let chars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'.split(''); let 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 let 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('');}对于第四中算法可以指定长度和基数。比如
// 8 character ID (base=2)uuid(8, 2) // "01001010"// 8 character ID (base=10)uuid(8, 10) // "47473046"// 8 character ID (base=16)uuid(8, 16) // "098F4D35"本文转载于简书 原文链接：https://www.jianshu.com/p/04ee4396edc3