function checkContact(form) {
 if (!checkinput('naam','Please fill in your name',form,type='string') ) {return false} ;
 if (!checkinput('email','Please fill in a correct email address',form,type='email') ) {return false} ;
 if (!checkinput('bericht','Please enter a message',form,type='string') ) {return false} ;
 return true;
}