// Basis functie om dom elementen mee op te halen

function tag(t){
	return document.getElementsByTagName(t);
}

var maandLengtes = new Array(31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);

function getPos(element_id){
	var positions = new Array();
	var element = document.getElementById(element_id);
	if (element != null){
		positions["x"] = element.style.left;
		positions["y"] = element.style.top;
	}
	return positions;
}

function buildDays(dag_id, maand_id, jaar_id){
	var dag_element = document.getElementById(dag_id);
	var maand_element = document.getElementById(maand_id);
	var jaar_element = document.getElementById(jaar_id);
	if (dag_element != null && maand_element != null && jaar_element != null){
		dag = 1;
		if (dag_element.options.length > 0){
			var dag = parseFloat(dag_element.options[dag_element.selectedIndex].value);
		}
		var maand = parseFloat(maand_element.options[maand_element.selectedIndex].value);
		var jaar = parseFloat(jaar_element.options[jaar_element.selectedIndex].value);
		var dagen = maandLengtes[(maand-1)];
		if(maand == 2 && isLeap(jaar)){
			dagen = 29;
		}
		dag_element.options.length = 0;
		var found = false;
		for(i = 1; i <= dagen; i++){
			var option = document.createElement("OPTION");
			var optionText = i;
			if (optionText < 10){
				optionText = "0"+optionText;
			}
			option.text = optionText;
			option.value = i;
			if (i == dag){
				option.selected = true;
				found = true;
			} else if(i == dagen && !found){
				option.selected = true;
			}
			dag_element.options.add(option);
		}
	}
}

function isLeap(jaar){
	if (jaar % 400 == 0){
		return true;
	} else if (jaar % 100 == 0){
		return false;
	} else if (jaar % 4 == 0){
		return true;
	} else {
		return false;
	}
}

function moveTo(elementId, x, y){
	var element = document.getElementById(elementId);
	if(element != null){
		element.style.position = "absolute";
		element.style.left = x;
		element.style.top = y;
	}
}

function isText(string){
	string = string.toLowerCase();
	var l = string.length;
	var allowed = "abcdefghijklmnopqrstuvwxyz";
	var valid = true;
	for(i = 0; i < string.length; i++){
		var letter = string.charAt(i);
		if(!allowed.indexOf(letter)){
			valid = false;
		}
	}
	return valid;
}

function isNumeric(number){
	var string = number+"";
	string = string.toLowerCase();
	var allowed = "0123456789";
	var valid = true;
	for(i = 0; i < string.length; i++){
		var nr = string.charAt(i);
		if(!allowed.indexOf(nr)){
			valid = false;
		}
	}
	return valid;
}

function isPhone(number){
	var string = number+"";
	string = string.toLowerCase();
	string.replace("-", "");
	string.replace(" ", "");
	if(isNumeric(string)){
		
	} else {
		return false;
	}
}

function isLength(string, length){
	if(string.length == length){
		return true;
	} else {
		return false;
	}
}

function isEmpty(string){
	if(string.length == 0){
		return true;
	} else {
		return false;
	}
}

function resizeWindow(w,h){
	window.resizeTo(w,h);
}

function clearText(e){
	if(e.value == 'Trefwoord...') {
		e.value = '';
	}
}
function fillEmpty(e){
	if(e.value == ''){
		e.value = 'Trefwoord...';
	}
}

function clearTextNewsletter(e){
	if(e.value == 'Uw E-mailadres') {
		e.value = '';
	}
}
function fillTextNewsletter(e){
	if(e.value == ''){
		e.value = 'Uw E-mailadres';
	}
}