// JScript source code
// Body Mass Index Calculator
// copyright 28th April 2006, by Stephen Chapman
// permission to use this Javascript on your web page is granted
// provided that all of the code in this script (including these
// comments) is used without any alteration
function valButton(btn) 
{
	var cnt = -1;
	for (var i=btn.length-1; i > -1; i--) 
	{   
		if (btn[i].checked) 
		{
			cnt = i; 
			i = -1;
		}
	}
	if (cnt > -1) 
		return btn[cnt].value;else return null;
}

function stripBlanks(fld) 
{
	var result = "";var c = 0;
	for (i=0; i < fld.length; i++) 
	{
		if (fld.charAt(i) != " " || c > 0) 
		{
			result += fld.charAt(i);
			if (fld.charAt(i) != " ") 
			c = result.length;
		}
	}
	return result.substr(0,c);
}

function calc(thisform) 
{
	var d = valButton(thisform.d);
	if (d == null) 
	{
		alert("You must choose centimetres/kg or inches/lb");
		return false;
	}
	cv = d.split(',');;
	var h = stripBlanks(thisform.h.value);
	if (h == '') 
	{
		alert("You must enter your height");
		thisform.h.focus();
		return false;
	}
	if (h != Number(h) || (h = Number(h*cv[0]/100)) < 1 || h > 2.5) 
	{
		alert("Invalid height entered");thisform.h.focus();
		return false;
	}
	var w = stripBlanks(thisform.w.value);
	if (w == '') 
	{
		alert("You must enter your weight");
		thisform.w.focus();
		return false;
	}
	if (w != Number(w) || (w = Number(w/cv[1])) < 25 || w > 250) 
	{
		alert("Invalid weight entered");
		thisform.w.focus();
		return false;
	} 
	thisform.f.value = Math.round(w / (h*h)*100)/100;
}