// enable / disable form elementen

function enableElement(elementName)
{
	var elements = document.getElementsByName(elementName);
	var x = elements.length;
	for (a = 0; a < x; a++) 
	{
		elements[a].disabled=false;
	}
}


function disableElement(elementName)
{
	var elements = document.getElementsByName(elementName);
	var x = elements.length;
	for (a = 0; a < x; a++) 
	{
		elements[a].disabled=true;
	}
}

function checkElement(elementName)
{
	var elements = document.getElementsByName(elementName);
	var x = elements.length;
	for (a = 0; a < x; a++) 
	{
		elements[a].checked=true;
	}
}

function uncheckElement(elementName)
{
	var elements = document.getElementsByName(elementName);
	var x = elements.length;
	for (a = 0; a < x; a++) 
	{
		elements[a].checked=false;
	}
}

// autotab naar volgend form element

function autoTab(input,len, e) {
  var keyCode = e.keyCode; 
  var filter = [0,8,9,16,17,18,37,38,39,40,46];
  if(input.value.length >= len && !containsElement(filter,keyCode)) {
    input.value = input.value.slice(0, len);
    input.form[(getIndex(input)+1) % input.form.length].focus();
  }

  function containsElement(arr, ele) {
    var found = false, index = 0;
    while(!found && index < arr.length)
    if(arr[index] == ele)
    found = true;
    else
    index++;
    return found;
  }

  function getIndex(input) {
    var index = -1, i = 0, found = false;
    while (i < input.form.length && index == -1)
    if (input.form[i] == input)index = i;
    else i++;
    return index;
  }
  return true;
}

// maxlength voor textarea

function imposeMaxLength(event, object, MaxLen){
    var key = event.keyCode ? event.keyCode : event.which;
    if(key == 8){
        // 8 is the keycode for the backspace key
        return true;
    }else{
        return (object.value.length <= MaxLen);
    }
}