// 
          How to get Unique Device ID with WinJS on WP8.1
This example shows how to get Unique Device ID with WinJS on Windows Phone 8.1:
          
          
function createDeviceId() {
          
    var deviceId = "";
          
    var packageSpecificToken =
          
        Windows.System.Profile.HardwareIdentification
          
            .getPackageSpecificToken(null);
          
    var hardwareId = packageSpecificToken.id;
          
    var dataReader =
          
        Windows.Storage.Streams.DataReader
          
            .fromBuffer(hardwareId);
          
          
    var array = new Array(hardwareId.length);
          
    dataReader.readBytes(array);
          
    for (var i = 0; i < array.length; i++) {
          
        deviceId += array[i].toString();
          
    }
          
    return deviceId;
          
}