关于javascript:js随机生成36位字符

uuid () {  var s = []  var hexDigits = '0123456789abcdef'  for (var 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]  var uuidA = s.join('')  return uuidA}