代码一：
/*!
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];
