function checkForm() {
  fname = document.getElementById("myFirstName").value;
  lname = document.getElementById("myLastName").value;
  phone = document.getElementById("myDaytimePhone").value;
  email = document.getElementById("myEmail").value;
 
  if (fname == "") {
    hideAllErrors();
    document.getElementById("fnameError").style.display = "inline";
    document.getElementById("myFirstName").select();
    document.getElementById("myFirstName").focus();
    return false;
  } else if (lname == "") {
    hideAllErrors();
    document.getElementById("lnameError").style.display = "inline";
    document.getElementById("myLastName").select();
    document.getElementById("myLastName").focus();
    return false;
  } else if (phone == "") {
    hideAllErrors();
    document.getElementById("phoneError").style.display = "inline";
    document.getElementById("myDaytimePhone").select();
    document.getElementById("myDaytimePhone").focus();
    return false;
  } else if (email.search(/^\w+((-\w+)|(\.\w+))*\@[A-Za-z0-9]+((\.|-)[A-Za-z0-9]+)*\.[A-Za-z0-9]+$/) == -1) {
    hideAllErrors();
    document.getElementById("emailError").style.display = "inline";
    document.getElementById("myEmail").select();
    document.getElementById("myEmail").focus();
    return false;
  }
  return true;
}
 
function hideAllErrors() {
  document.getElementById("fnameError").style.display = "none"
  document.getElementById("lnameError").style.display = "none"
  document.getElementById("phoneError").style.display = "none"
  document.getElementById("emailError").style.display = "none"
}