// 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("Debes seleccionar el formato de medida, kg o libras (lb)");
	thisform.d.focus();
	return false;
}

	cv = d.split(',');
	var h = stripBlanks(thisform.h.value);

if (h == '') {
	alert("Debes definir tu altura");
	thisform.h.focus();
	return false;
	} 

if (h != Number(h) || (h = Number(h*cv[0]/100)) < 1 || h > 2.5) {
	alert("Altura no válida");
	thisform.h.focus();
	return false;
	}

var w = stripBlanks(thisform.w.value);

if (w == '') {
	alert("Debes definir tu peso");
	thisform.w.focus();
	return false;
	}

if (w != Number(w) || (w = Number(w/cv[1])) < 25 || w > 250) {alert("Peso no válido");
	thisform.w.focus();
	return false;
} 

thisform.f.value = Math.round(w / (h*h)*100)/100;}