String.prototype.endsWith = function(s) 
{
	return this.length >= s.length && this.substr(this.length - s.length) == s;
}

String.prototype.startsWith = function(s) 
{
	return this.length >= s.length && this.substr(0, s.length) == s;
}

function round(value,precision)
{
	var exp = Math.pow(10,precision);
	
	return Math.round(value*exp)/exp;
}

var unitRatios = new Array();

function addUnit(name,ratio)
{
	unitRatios[name] = ratio;
}

addUnit("Ton",1000000);
addUnit("Kilogram",1000);
addUnit("Dekagram",10);
addUnit("Gram",1)
addUnit("Milligram",0.001);
addUnit("Mikrogram",0.000001);

addUnit("Amu",1.66053892173e-24);

addUnit("TonUK",1016046.9);
addUnit("TonUS",907184.740);
addUnit("HundredweightUK",50802.345);
addUnit("HundredweightUS",45359.2370);
addUnit("Stone",6350.29318);
addUnit("Pound",453.59237);
addUnit("Ounce",28.3495231);
addUnit("Grain", 0.06479891);

addUnit("Kwintal",100000);
addUnit("Carat",0.2);
addUnit("TroyOunce",31.1034768);


addUnit("Cetnar",64832);
addUnit("Kamien",12966.4);
addUnit("Funt",405.2);
addUnit("Grzywna",202.6);
addUnit("Lut",12.6625);

function initialize()
{
	document.chooseForm.unitKilogram.value = 1;
	recalculate(document.chooseForm.unitKilogram);
}

function recalculate(field)
{
	if(field.value.indexOf(',')>0)
		field.value = field.value.replace(',','.');

	var numberRegExp = new RegExp("^[0-9\.,-e\+]*$");		
	if(!numberRegExp.test(field.value))
		field.value = field.value.replace(/[^0-9\.,-e\+]*/ig,'');	
	
	//check for double decimal separator
	var firstSep = field.value.indexOf(".");
	var secondSep = firstSep>0?field.value.indexOf(".",firstSep+1):-1;
	if(firstSep>0 && secondSep>firstSep)
	{
		field.value = field.value.substring(0,secondSep);
	}
	
	if(field.value[field.value.length-1]=='.')
		return;
	
	var reset = false;
	if(field.value.length == 0)
	{
		reset = true;
	}
	
	var ratio = field.value * unitRatios[field.id.substring(4)];
		
   for(var i = 0; i < document.chooseForm.elements.length; i++)
   {
		var currentElement = document.chooseForm.elements[i];
		
		if(currentElement == field)
			continue;
		
		if(reset)
		{
			currentElement.value = '';
			continue;
		}
				
		
		var result = (ratio / unitRatios[currentElement.id.substring(4)]).toPrecision(7);
		if(result>0.0000001 && result<10000000)
			result = round(result,6);
		
		currentElement.value = result;
	}
}

function selectInput(field)
{
	addClass(field,"form-selected");
	
	for(var i = 0; i < document.chooseForm.elements.length; i++)
   {
		var currentElement = document.chooseForm.elements[i];
		
		if(currentElement == field)
			continue;
			
		removeClass(currentElement,"form-selected");
	}
}

function addClass(item, classname) 
{
    var obj = item
    if (typeof item=="string") {
        obj = document.getElementById(item)
    }
    obj.className += " " + classname
}

function removeClass(item, classname) 
{
    var obj = item
    if (typeof item=="string") {
        obj = document.getElementById(item)
    }
    var classes = ""+obj.className
    while (classes.indexOf(classname)>-1) {
        classes = classes.replace (classname, "")
    }
    obj.className = classes
}