function init_all_boxes()
{
	var objs = document.getElementsByName(this.name);
	for (var i = 0; i < objs.length; i++)
	{
		objs[i].value = "";
	}
} 

function set_handlers()
{
	var objs = document.getElementsByName('weight');
	for (var i = 0; i < objs.length; i++)
	{
		objs[i].onfocus = init_all_boxes;
	}
}

function on_weight_click()
{
	var grams = get_value_or_zero('grams');
	var kg = get_value_or_zero('kg');
	var ounce = get_value_or_zero('ounce');
	var libra = get_value_or_zero('libra');
	
	var OUNCE_IN_GRAMS = 28.3495231;
	var KG_IN_GRAMS = 1000;
	var LIBRA_IN_GRAMS = 453.59237;
	
	if (kg)
		grams = kg * KG_IN_GRAMS;
		
	if (grams)
	{	
		kg = grams / KG_IN_GRAMS;
		ounce = grams / OUNCE_IN_GRAMS;
		libra = grams / LIBRA_IN_GRAMS;
	}
	else
	if (ounce)
	{
		grams = ounce * OUNCE_IN_GRAMS;
		kg = grams / KG_IN_GRAMS;
		libra = grams / LIBRA_IN_GRAMS;
	}
	else
	if (libra)
	{
		grams = libra * LIBRA_IN_GRAMS;
		kg = grams / KG_IN_GRAMS;
		ounce = grams / OUNCE_IN_GRAMS;
	}
	
	if (grams < 0)
	{
		alert("המשקל שהזנת שלילי. אין משמעות למשקלים שליליים");
		return;
	}
	
	if (grams == Math.floor(grams))
		set_value('grams',format_number(grams, 0));
	else
		set_value('grams',format_number(grams, 2));
	set_value('kg', format_number(kg, 4));
	set_value('ounce', format_number(ounce, 4));
	set_value('libra', format_number(libra, 4));
}