RFC Compliant GUID Module

math.uuid.js

/*!
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"
 */
var GUID = 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);
            });
        };

    return {
        create: Math.uuid,
        createFast: Math.uuidFast,
        createCompact: Math.uuidCompact
    }
}();