function checkText(el,mes){
	if (el.value == "") {
		alert( mes);
		el.focus(); 
		return false ;
	}
	return true;
}
function checkRadio(el,mes){
  if(el)
  var result = 0
  for(var i=0; i<el.length; i++){
    if(el[i].checked==true ){ 
      result = 1
    }
  }
  if(result == 0){
    alert(  mes  );
    return false;
  }
  return true;
}
function checkMail(el,force){
  var regex = el.value
  if(force || regex !=''){
	  if(force && regex == ''){
			alert( "Please fill in your E-mail address" );
			el.focus();
			return false ;
		}
	  var valid = new RegExp("^[a-z]+([.]?[a-z0-9_-]+)*[@]([a-z0-9_-]+[.])+([a-z]{2,4})$").exec(regex);
		if(!valid) { 
	    alert( "The given E-mail address is not valid. Capitalization is not allowed");
	    el.focus();
	    return false;
	  }
	}
	return true;
}

function confirmCheckbox(el,mes){
  if(el.checked){
    return confirm(mes);
  }
  return true
}
function checkBox(el,mes){
  if(!(el.checked)){
    alert(mes);
    el.focus();
    return false;
  }
  return true;
}
function checkPC(el,force){
  var regex = el.value
  if(force || regex !=''){
	  if(force && regex == ''){
			alert( "Vul uw postcode in.\n (bv. 1111AA)" );
			el.focus();
			return false ;
		}
	  var valid = new RegExp("^[0-9]{4}[a-zA-z]{2}$").exec(regex);
		if(!valid) { 
	    alert( "Het door uw ingevoerder postcode is ongeldig (bv. 1111AA)." );
	    el.focus();
	    return false;
	  }
	}
	return true;
}
function checkPhoneNumber(el,force){
  var regex = el.value
  if(force || regex !=''){
	  if(force && regex == ''){
			alert( "Vul uw nummer in.\n(bv. 0206666666)" );
			el.focus();
			return false ;
		}
	  var valid = new RegExp("^[0-9]{10}$").exec(regex);
		if(!valid) { 
	    alert( "Het door u ingevoerde nummer is ongeldig.\n Voer uw nummer als volgt zonder streepjes in: 0206666666" );
	    el.focus();
	    return false;
	  }
	}
	return true;
}
function checkNumber(el,force){
  var regex = el.value
  if(force || regex !=''){
	  if(force && regex == ''){
			alert( "Please fill in a number." );
			el.focus();
			return false ;
		}
	  var valid = new RegExp("^[0-9]*$").exec(regex);
		if(!valid) { 
	    alert( "The given number is not valid." );
	    el.focus();
	    return false;
	  }
	}
	return true;
}
function checkDate(el,force){
  var regex = el.value
  if(force || regex !=''){
	  if(force && regex == ''){
			alert( "Vul uw datum in." );
			el.focus();
			return false ;
		}
	  var valid = new RegExp("(0[1-9]|[12][0-9]|3[01])[-](0[1-9]|1[012])[-](19|20)[0-9][0-9]").exec(regex);
		if(!valid) { 
	    alert( "Het door u ingevoerde datum is ongeldig. bv(dd-mm-yyyy)" );
	    el.focus();
	    return false;
	  }
	}
	return true;
}