js 生成UUID的几种方法

简介:
UUID(Universally Unique IDentifier) 全局唯一标识符。
UUID是一种由算法生成的二进制长度为128位的数字标识符。UUID
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UUID。
1.第一种

function guid() {
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);
});
}
guid() // "a1ca0f7b-51bd-4bf3-a5d5-6a74f6adc1c7"

2.第二种

function uuid() {
var s = [];
var hexDigits = "0123456789abcdef";
for (var 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] = "-";

var uuid = s.join("");
return uuid;
}
uuid() // "ffb7cefd-02cb-4853-8238-c0292cf988d5"

3.第三种

function guid2() {
function S4() {
    return (((1 + Math.random()) * 0x10000) | 0).toString(16).substring(1);
}
return (S4() + S4() + "-" + S4() + "-" + S4() + "-" + S4() + "-" + S4() + S4() + S4());
}
guid2() // "748eea29-f842-4af9-a552-e1e1aa3ed979"

4.第四种

// 指定长度和基数
function uuid2(len, radix) {
var chars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'.split('');
var 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('');
}
uuid2(16, 16) // "277571702EE33E11"

5.第五种

function uuid() {
var s = [];
var hexDigits = "0123456789abcdef";
for (var i = 0; i < 32; 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];
var uuid = s.join("");
return uuid;
}