function isEmail(str) {
  // are regular expressions supported?
  var supported = 0;
  if (window.RegExp) {
    var tempStr = "a";
    var tempReg = new RegExp(tempStr);
    if (tempReg.test(tempStr)) supported = 1;
  }
  if (!supported) 
    return (str.indexOf(".") > 2) && (str.indexOf("@") > 0);
  var r1 = new RegExp("(@.*@)|(\\.\\.)|(@\\.)|(^\\.)");
  var r2 = new RegExp("^.+\\@(\\[?)[a-zA-Z0-9\\-\\.]+\\.([a-zA-Z]{2,3}|[0-9]{1,3})(\\]?)$");
  return (!r1.test(str) && r2.test(str));
}

function checkContactForm () {
	
	if (document.getElementById("naam").value == "") {
		document.getElementById("naam").focus();
		alert("Vul naam in" );
		return false;
	}
	else if (!isEmail(document.getElementById("email").value) && document.getElementById("email").value != "") {
		document.getElementById("email").focus();
		alert("Email niet in juist formaat" );
		return false;
	} 
	else if ((document.getElementById("telefoonnummer").value == "") ||(document.getElementById("telefoonnummer").value.length < 7) ) {
		document.getElementById("telefoonnummer").focus();
		alert("Vul telefoonnummer in" );
		return false;
	}
	else {

                view = -1         
                for (i=0; i<Contact.vest.length; i++) {         
                   if (Contact.vest[i].checked) {         
                    view = i               
                    }            
                 }

                if (view == -1) {            
                   alert("Kies een vestiging....")      
                   return false;
                }
                else
                {
                   document.Contact.button_action.value = 'SAVE';
		   return true;
                }
	}	
}