<script type="text/javascript">
<!--

var calculation = "";
var resultDone = false;

function addToCalc(val) {
  if(isNaN(val) && isNaN(calculation.substring(calculation.length-1, calculation.length)))
    return false;

  if(!isNaN(val) && resultDone) {
    resetCalc();
    resultDone = false;
  } else if(isNaN(val) && resultDone) {
    resultDone = false;
  }
  calculation += val;
  showResult();
}

function addToCalcDirect(val) {
  calculation = val;
}

function resetCalc() {
  calculation = "";
  showResult();
}

function positiveNegative() {
  if(calculation.substring(0, 1) == "-")
    calculation = calculation.substring(1, calculation.length);
  else
    calculation = "-" + calculation;
  showResult();
}

function calculate() {
  if(calculation != "") {
    try {
      calculation = eval(calculation);
    } catch(e) {
      reportError("Error!");
    }
    resultDone = true;
    showResult();
  }
  else
    return false;
}

function percentage() {
  try {
    calculation = eval(calculation) / 100;
  } catch(e) {
    reportError("Error!");
  }
  resultDone = true;
  showResult();
}

function squareRoot()
{
  try {
    calculation = Math.sqrt(eval(calculation));
  } catch(e) {
    reportError("Error!");
  }
  resultDone = true;
  showResult();
}

function showResult() {
  calculation = calculation.toString();
  if(calculation == "NaN") {
    reportError("Error!");
  } else {
    document.getElementById("result").value = calculation;
  }
}

function reportError(msg) {
  calculation = msg;
  document.getElementById("result").value = msg;
}

function closeCalculator() {
  document.getElementById("calculator").style.display = "none";
}

function about() {
  msg = "เครื่องคิดเลข (Calculator)\n===============\n\n";
  msg += "พัฒนาโดย James Crooke\nhttp://www.cj-design.com";
  alert(msg);
}

var ie = document.all;
var ns6 = document.getElementById && !document.all;
var dragapproved=false;
var z, x, y;

function move(e) {
  if (dragapproved) {
    z.style.left=ns6? temp1+e.clientX-x: temp1+event.clientX-x;
    z.style.top=ns6? temp2+e.clientY-y : temp2+event.clientY-y;
    return false;
  }
}

function drags(e) {
  if (!ie&&!ns6)
  return;
  var firedobj = ns6? e.target : event.srcElement;
  var topelement = ns6? "HTML" : "BODY";
  while (firedobj.tagName != topelement&&firedobj.className != "drag") {
    firedobj = ns6? firedobj.parentNode : firedobj.parentElement;
  }
  if (firedobj.className == "drag") {
    dragapproved = true;
    z = firedobj;
    temp1 = parseInt(z.style.left+0);
    temp2 = parseInt(z.style.top+0);
    x = ns6? e.clientX: event.clientX;
    y = ns6? e.clientY: event.clientY;
    document.onmousemove=move;
    return false;
  }
}
document.onmousedown=drags;
document.onmouseup=new Function("dragapproved=false");
// -->
</script>