// JavaScript Document
function checkForm() {
firstname = document.getElementById("firstname").value;
lastname = document.getElementById("lastname").value;
email = document.getElementById("email").value;

if (firstname == "") {
hideAllErrors();
document.getElementById("firstnameError").style.display = "inline";
document.getElementById("firstname").select();
document.getElementById("firstname").focus();
  return false;
  }
  else if
  (lastname == "") {
  hideAllErrors();
  document.getElementById("lastnameError").style.display = "inline";
  document.getElementById("lastname").select();
  document.getElementById("lastname").focus();
  return false;
  }
  else if
  (email.indexOf('@') == -1 || email.indexOf('.') == -1 || email.length <7) {
  hideAllErrors();
  document.getElementById("emailError").style.display = "inline";
  document.getElementById("email").select();
  document.getElementById("email").focus();
  return false;
  } 
  return true;
}

function hideAllErrors() {
document.getElementById("firstnameError").style.display = "none"
document.getElementById("lastnameError").style.display = "none"
document.getElementById("emailError").style.display = "none"
}

//function to check valid email address
function isValidEmail(strEmail){
  validRegExp = /^[^@]+@[^@]+.[a-z]{2,}$/i;
  strEmail = document.forms[0].email.value;

   // search email text for regular exp matches
    if (strEmail.search(validRegExp) == -1) 
   {
      alert('A valid e-mail address is required.\nPlease amend and retry');
      return false;
    } 
    return true; 
}