SPI question

Updated on my site. Code is:

exports.connect = function(spi,cs) {
  return new MAX31855(spi,cs);
};

function MAX31855(spi,cs) {
  this.spi=spi;
  this.cs=cs;
}

MAX31855.prototype.getTemp = function () {
  var d = SPI1.send("\0\0\0\0",this.cs); 
  if (d.charCodeAt(1) & 1)  {
    var trtn = {fault: (d.charCodeAt(3) & 7)};
    switch (trtn.fault) {
      case 1:
        trtn.faultstring="No probe detected";
        break;
      case 3:
        trtn.faultstring="Probe shorted to Ground";
        break;
      case 4:
        trtn.faultstring="Probe shorted to VCC";
        break;
    }
    return trtn;
  } else {
    return {temp: (d.charCodeAt(0)<<6 | d.charCodeAt(1)>>2)*0.25, fault: 0};
  }
};