immutable-js/src/util/guid.js

Immutable types in JavaScript

/**
 *  Copyright (c) 2015, Jan Biasi.
 *  All rights reserved.
 *
 *  This source code is licensed under the BSD-style license found in the
 *  LICENSE file in the root directory of this source tree. An additional grant
 *  of patent rights can be found in the PATENTS file in the same directory.
 */

/**
 * RFC4122 version 4 compliant solution that solves that issue by offsetting
 * the first 13 hex numbers by a hex portion of the timestamp.
 */
export default function guid() {
    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;
}