js生成uuid的方法
找到三种生成uuid方法,如下:/*!Math.uuid.js (v1.4)http://www.broofa.commailto:robert@broofa.comCopyright (c) 2010 Robert KiefferDual licensed under the MIT and GPL licenses.*//** Generate a random uu
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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。
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