function getUUid() { const s = []; const hexDigits = '0123456789abcdef'; for (let i = 0; i < 36; i++) { s[i] = hexDigits.substr(Math.floor(Math.random() * 0x10), 1); } s[14] = '4'; s[19] = hexDigits.substr((s[19] & 0x3) | 0x8, 1); s[8] = s[13] = s[18] = s[23] = '-'; return s.join(''); }