function checkform(form) {

  if (form.name.value == "") {
    alert( "Please enter your name." );
    form.name.focus();
    return false ;
  }
  
  if (form.phone.value == "") {
    alert( "Please enter your phone number." );
    form.phone.focus();
    return false ;
  }
  
   if (form.email.value == "") {
    alert( "Please enter your email address." );
    form.email.focus();
    return false ;
  }
  
  return true ;
}