(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); }); }; })();