UUID(uuid)js 生成

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2^128（3.4×10^38）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。

在生成一些节点的时候需要通过唯一ID来标记，有如下高票答案可供参考

 

/*

* 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);

});

};

})();

 

另外还有几种写法：

 

function generateUUID() {

var d = new Date().getTime();

var uuid = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {

var r = (d + Math.random()*16)%16 | 0;

d = Math.floor(d/16);

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

});

return uuid;

};

答案下面的评论云：这个方案下的碰撞率不及1/2^^122

另外给大家推荐几种算法

算法2

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);

});

}

算法3

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4

function uuid(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('');

}

这个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"

算法5

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;

}

当然了，个人还是推荐算法一的，小伙伴们可以根据自己的需求来进行选择。