//regel berekenen
function calc(objselect,helperid) {
	var form         = document.rekenformulier;
	var tprijs	     = 0;
	var resultname   = objselect.id.replace("field_", "result_");
	var helpername	 = "helper_" + helperid 
	var ihelpervalue = 0;
	var iresultvalue =  parseFloat(objselect.value);
	
	
	//controleer input
	if (isNaN(iresultvalue)) {
		iresultvalue = 0;
	}
	
	if ((helperid > -1) && iresultvalue > 0) {
		ihelpervalue = parseFloat(document.getElementById(helpername).value);
		if (isNaN(ihelpervalue)) {
			ihelpervalue = 0;
		}
		iresultvalue = iresultvalue * ihelpervalue;
	}
	
	//waarde instellen
	document.getElementById(resultname).value = CurrencyFormatted(iresultvalue);
	
	//totalen doorberekenen
	calcform(form);
}

//totalen berekenen
function calcform(f) {
	var tprijs = 0;
	
	for ( var i = 0; i < f.length ; i++ ) {
		var element = f[i];
		if ( element.id.indexOf('result_')!=-1 ) {
			tprijs += parseFloat(element.value);
		}
	}
	
	//totaal instellen
	f.totale_kosten.value = CurrencyFormatted(tprijs);	
}









//-------------------------------------------------------------------
// isInteger(value)
//   Returns true if value contains all digits
//-------------------------------------------------------------------
function isInteger(val){
	if (isBlank(val)){return false;}
	for(var i=0;i<val.length;i++){
		if(!isDigit(val.charAt(i))){return false;}
		}
	return true;
	}

//-------------------------------------------------------------------
// isDigit(value)
//   Returns true if value is a 1-character digit
//-------------------------------------------------------------------
function isDigit(num) {
	if (num.length>1){return false;}
	var string="1234567890";
	if (string.indexOf(num)!=-1){return true;}
	return false;
	}

//-------------------------------------------------------------------
// isBlank(value)
//   Returns true if value only contains spaces
//-------------------------------------------------------------------
function isBlank(val){
	if(val==null){return true;}
	for(var i=0;i<val.length;i++) {
		if ((val.charAt(i)!=' ')&&(val.charAt(i)!="\t")&&(val.charAt(i)!="\n")&&(val.charAt(i)!="\r")){return false;}
		}
	return true;
	}

function CurrencyFormatted(amount)
{
	var i = parseFloat(amount);
	if(isNaN(i)) { i = 0.00; }
	var minus = '';
	if(i < 0) { minus = '-'; }
	i = Math.abs(i);
	i = parseInt((i + .005) * 100);
	i = i / 100;
	s = new String(i);
	if(s.indexOf('.') < 0) { s += '.00'; }
	if(s.indexOf('.') == (s.length - 2)) { s += '0'; }
	s = minus + s;
	return s;
}