bytesToUuid.js

/**
 * Convert array of 16 byte values to UUID string format of the form:
 * XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX
 */
var byteToHex = [];
for (var i = 0; i < 256; ++i) {
  byteToHex[i] = (i + 0x100).toString(16).substr(1);
}

function bytesToUuid(buf, offset) {
  var i = offset || 0;
  var bth = byteToHex;
  // join used to fix memory issue caused by concatenation: https://bugs.chromium.org/p/v8/issues/detail?id=3175#c4
  return ([
    bth[buf[i++]], bth[buf[i++]],
    bth[buf[i++]], bth[buf[i++]], '-',
    bth[buf[i++]], bth[buf[i++]], '-',
    bth[buf[i++]], bth[buf[i++]], '-',
    bth[buf[i++]], bth[buf[i++]], '-',
    bth[buf[i++]], bth[buf[i++]],
    bth[buf[i++]], bth[buf[i++]],
    bth[buf[i++]], bth[buf[i++]]
  ]).join('');
}

module.exports = bytesToUuid;