var _ONE=1;
function Switch(item,OldChar,NewChar)
{
  var _ret="";
  var _flag=0;
  var _item=item.split("");
  for(var i=0;i<_item.length;i++)
  {
    if(!_flag&&_item[i]==OldChar)
	{
	  _item[i]=NewChar;
      _flag=_ONE;
	}
	_ret+=_item[i];
  }
  return(_ret);
}

function bmi() {
	var temp = document.form_bmi.weight.value;
	document.form_bmi.weight.value = Switch(temp,",",".");
	if(document.form_bmi.weight.value == "") {
		alert("Du må skrive inn din vekt i kilo");
		document.form_bmi.weight.focus();
	} else if(document.form_bmi.height.value == "") {
		alert("Du må skrive inn din høyde i cm.");
		document.form_bmi.height.focus();
	} else {
	
		var h = document.form_bmi.height.value;
		var w = document.form_bmi.weight.value;
		
		var bmindx=(w/eval(h*h))*10000;
		document.form_bmi.result.value = Math.round(bmindx);
	}
}