/**
 * Generates a UUID.
 * @returns {string} a uuid.
 */
export default function generateUUID() {
    let d = new Date().getTime();
    let d2 = (performance && performance.now && (performance.now() * 1000)) || 0;
    return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, c => {
        let r = Math.random() * 16;
        if (d > 0) {
            r = (d + r) % 16 | 0;
            d = Math.floor(d / 16);
        } else {
            r = (d2 + r) % 16 | 0;
            d2 = Math.floor(d2 / 16);
        }
        return (c == 'x' ? r : (r & 0x7 | 0x8)).toString(16);
    });
};