微信小程序CRC16校验，通过测试，好用

function TypedArrays(Type,Bin,begin,Num)
{  
      switch(Type)
    {
        case 0:    return new Int8Array(Bin, begin ,Num)[0];
        case 1:   return new Uint8Array(Bin, begin ,Num)[0];
        case 2:   return new Int16Array(Bin, begin ,Num)[0];
        case 3:  return new Uint16Array(Bin, begin ,Num)[0];
        case 4:   return new Int32Array(Bin, begin ,Num)[0];
        case 5:  return new Uint32Array(Bin, begin ,Num)[0];
        case 6: return new Float32Array(Bin, begin ,Num)[0];
        case 7: return new Float64Array(Bin, begin ,Num)[0];
        default: return -1;
    }
}

var crc16= function (buffer,len)
{
    var crc = 0xFFFF;
    for (var pos = 0; pos < len; pos++)
    {
          var x= 0x0000;
          x=TypedArrays(1,buffer,pos,1);
          crc ^= x// XOR byte into least sig. byte of crc
        for (var i = 8; i != 0; i--)   // Loop over each bit
        {
            if ((crc & 0x0001) != 0)   // If the LSB is set
            {
                crc >>= 1; // Shift right and XOR 0xA001
                crc ^= 0xA001;
            }
            else // Else LSB is not set
            {
                crc >>= 1;    // Just shift right
            }
          
        }     
    }    //高低字节转换

    return crc;
}