function resetanswer(){
  document.MainForm.result.value = "";
  document.MainForm.what.value="";
}

function myCon(){
  var v1, v2, ConVal, TheAnswer;
  
  v1 = document.MainForm.what.value;
  v1 = stripBad(v1);
  v1 = parseFloat(v1);
  if (isNaN(v1)) v1 = 1;
  document.MainForm.what.value = v1;

  ConVal = document.MainForm.from[document.MainForm.from.selectedIndex].value;

  if (ConVal == 1){
    v2 = v1 / 18;
	v2 = Math.round(v2 *100000)/100000;
	v2 = comma(v2);
	v1 = comma(v1);
    TheAnswer = v1 + " mg/dl = " + v2 + " mmol/l";
  } else {
    v2 = v1 * 18;
	v2 = Math.round(v2 *100000)/100000;
	v2 = comma(v2);
	v1 = comma(v1);
    TheAnswer = v1 + " mmol/l = " + v2 + " mg/dl";
  }
  
  document.MainForm.result.value = TheAnswer;
  
}

function stripBad(string) {
    for (var i=0, output='', valid="eE-0123456789."; i<string.length; i++)
       if (valid.indexOf(string.charAt(i)) != -1)
          output += string.charAt(i)
    return output;
} 

function comma(num) {
 var n = Math.floor(num);
 var myNum = num + "";
 var myDec = ""
 
 if (myNum.indexOf('.',0) > -1){
  myDec = myNum.substring(myNum.indexOf('.',0),myNum.length);
 }

  var arr=new Array('0'), i=0; 
  while (n>0) 
    {arr[i]=''+n%1000; n=Math.floor(n/1000); i++;}
  arr=arr.reverse();
  for (var i in arr) if (i>0) //padding zeros
    while (arr[i].length<3) arr[i]='0'+arr[i];
  return arr.join() + myDec;
}