// JavaScript Document


function formCheck(f)
{
 
	if(f.naam.value == "") 
	{
		alert("Het veld 'Naam' is verplicht");
		return false;
	}
	
	if(f.telefoonnummer.value == "") 
	{
		alert("Het veld 'Telefoonnummer' is verplicht");
		return false;
	}
	
		
	if(!ParseUSNumber(f.telefoonnummer.value))
	{
		return false;
	}

function ParseUSNumber(PhoneNumberInitialString)
 {
    var FmtStr="";
    var index = 0;
    var LimitCheck;

    LimitCheck = PhoneNumberInitialString.length;
    while (index != LimitCheck)
      {
        if (isNaN(parseInt(PhoneNumberInitialString.charAt(index))))
          { }
        else
          { FmtStr = FmtStr + PhoneNumberInitialString.charAt(index); }
        index = index + 1;
      }
    if (FmtStr.length == 10)
      {
        FmtStr = "(" + FmtStr.substring(0,3) + ") " + FmtStr.substring(3,6) + "-" + FmtStr.substring(6,10);
      }
    else
      {{
        FmtStr=PhoneNumberInitialString;
        alert("Het telefoonnummer moet uit exact 10 cijfers bestaan");
      }
     return false;
  }
		
	return FmtStr; 
	}
	

}