JS - 生成UUID

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('');

}

这个可以指定长度和基数。比如：

// 8 character ID (base=2)

uuid(8, 2) // "01001010"

// 8 character ID (base=10)

uuid(8, 10) // "47473046"

// 8 character ID (base=16)

uuid(8, 16) // "098F4D35"