function confirmLogout() {

    if (confirm("Weet u zeker dat u zich wilt afmelden ?")) {

      document.location='aanmelden.php?logout';

    }

}



function checkIfEmpty(field) {

 if (document.getElementById(field).value != "") {

   document.getElementById(field).style.backgroundColor = "";

   return true;

 } else {

//   alert(field + " is een verplicht veld");

//   document.getElementById(field).style.backgroundColor = "#FF6666";

   document.getElementById(field).focus();

	return false;

 }

}



function IsEmailValid(checkThisEmail) {

	var myEMailIsValid = true;

	var myAtSymbolAt = document.getElementById(checkThisEmail).value.indexOf('@');

	var myLastDotAt = document.getElementById(checkThisEmail).value.lastIndexOf('.');

	var mySpaceAt = document.getElementById(checkThisEmail).value.indexOf(' ');

	var myLength = document.getElementById(checkThisEmail).length;

	

	

	// at least one @ must be present and not before position 2

	// @yellow.com : NOT valid

	// x@yellow.com : VALID

	

	if (myAtSymbolAt < 1 ) 

	 {myEMailIsValid = false}

	

	// at least one . (dot) afer the @ is required

	// x@yellow : NOT valid

	// x.y@yellow : NOT valid

	// x@yellow.org : VALID

	

	if (myLastDotAt < myAtSymbolAt) 

	 {myEMailIsValid = false}

	

	// at least two characters [com, uk, fr, ...] must occur after the last . (dot)

	// x.y@yellow. : NOT valid

	// x.y@yellow.a : NOT valid

	// x.y@yellow.ca : VALID

	

	if (myLength - myLastDotAt <= 2) 

	 {myEMailIsValid = false}

	

	

	// no empty space " " is permitted (one may trim the email)

	// x.y@yell ow.com : NOT valid

	

	if (mySpaceAt != -1) 

	 {myEMailIsValid = false}

	

	

	if (myEMailIsValid == true) {

//		document.getElementById(checkThisEmail).style.backgroundColor = "white";

		return true;

	} else {

    	//alert("email is not correct");

//    	document.getElementById(checkThisEmail).style.backgroundColor = "#FFCCCC";

		document.getElementById(checkThisEmail).focus();

		return false;

	}

}





function checkNieuwsbrief() {

    if (IsEmailValid("email")) {

        return true;            

    } else {

        alert("E-mail adres is niet correct ingevuld !");

        return false;

    }

}



function OpenWin(mypage,myname,w,h,features) {

     if(screen.width){

     var winl = (screen.width-w)/2;

     var wint = (screen.height-h)/2;

     }else{winl = 0;wint =0;}

     if (winl < 0) winl = 0;

     if (wint < 0) wint = 0;

     var settings = 'height=' + h + ',';

     settings += 'width=' + w + ',';

     settings += 'top=' + wint + ',';

     settings += 'left=' + winl + ',';

     settings += features;

     win = window.open(mypage,myname,settings);

     win.window.focus();

   }



   function IsNumeric(sText) {

     var ValidChars = "0123456789";

     var IsNumber=true;

     var Char;

      for (i = 0; i < sText.length && IsNumber == true; i++) { 

         Char = sText.charAt(i); 

         if (ValidChars.indexOf(Char) == -1){

//    	  alert('Het gekozen aantal is niet correct')

          document.getElementById(sText).focus();

             return false;

         }

      }

      if (sText > 0) {

      	return true;

      } else {

  ///    	alert('Het gekozen aantal is niet correct');

          document.getElementById(sText).focus();

          return false;

      }

    }  



  	function previewPicBig() {        

        if (document.getElementById('product_image_big').value == "") {

         //   alert("U moet eerst een bestand selecteren.");		

        } else {

            document.getElementById('preBig').src = document.getElementById('product_image_big').value;	

        }

    }

    

      	function previewPic() {

			if (document.getElementById('userfile').value == "") {

				alert("U moet eerst een bestand selecteren.");		

			} else {

				document.getElementById('pre').src = document.getElementById('userfile').value;	

			}

		}

        

        function checkFile() {

			if (document.getElementById('userfile').value == "") {

				alert("U moet eerst een bestand selecteren.");		

			    return false;

            } else {

                document.getElementById('uploaden').style.visibility = 'visible';

   			    return true;

            }        

        }