/* uuid生成器 */
export function uuid(len, radix) {
  var chars =
    '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'.split('')
  var 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('')
}