function checkField(sFieldId, sAlertId) {
 document.getElementById(sAlertId).innerHTML = "";
 sFieldContent = document.getElementById(sFieldId).value;
 sRegx = /^ *$/;
 iPos = sFieldContent.search(sRegx);
 if (iPos > -1) {
  bFormCorrect = false;
  document.getElementById(sAlertId).innerHTML = "Required information";
}}

function checkPhoneFields(sAreaFieldId, sExchangeFieldId, sPhoneFieldId, sAlertId) {
 document.getElementById(sAlertId).innerHTML = "";
 sAreaFieldContent = document.getElementById(sAreaFieldId).value;
 sExchangeFieldContent = document.getElementById(sExchangeFieldId).value;
 sPhoneFieldContent = document.getElementById(sPhoneFieldId).value;
 sTotalFieldContent = sAreaFieldContent + sExchangeFieldContent + sPhoneFieldContent;
 if (sTotalFieldContent == "") {
  bFormCorrect = false;
  document.getElementById(sAlertId).innerHTML = "Required information";
 }
 else {
  if (sAreaFieldContent == "" || sExchangeFieldContent == "" || sPhoneFieldContent == "") {
   bFormCorrect = false;
   document.getElementById(sAlertId).innerHTML = "Please fill in all fields";
  }
  else {
   sRegx = /^.{10}$/;
   iPos = sTotalFieldContent.search(sRegx);
   if (iPos == -1) {
    bFormCorrect = false;
    document.getElementById(sAlertId).innerHTML = "Format: xxx-xxx-xxxx";
   }
   else {
    sRegx = /^[0-9]{10}$/;
    iPos = sTotalFieldContent.search(sRegx);
    if (iPos == -1) {
     bFormCorrect = false;
     document.getElementById(sAlertId).innerHTML = "Please write digits only";
}}}}}

function checkEmailField(sFieldId, sAlertId) {
 document.getElementById(sAlertId).innerHTML = "";
 sFieldContent = document.getElementById(sFieldId).value;
 sRegx = /^ *$/;
 iPos = sFieldContent.search(sRegx);
 if (iPos > -1) {
  bFormCorrect = false;
  document.getElementById(sAlertId).innerHTML = "Required information";
 }
 else {
  sRegx = /^ +| +$/;
  iPos = sFieldContent.search(sRegx);
  if (iPos > -1) {
   bFormCorrect = false;
   document.getElementById(sAlertId).innerHTML = "Please remove spaces";
  }
  else {
   sRegx = /^[-0-9_a-z]+(\.[-0-9_a-z]+)*@[-0-9a-z]+(\.[-0-9a-z]{2,})+$/i;
   iPos = sFieldContent.search(sRegx);
   if (iPos == -1) {
    bFormCorrect = false;
    document.getElementById(sAlertId).innerHTML = "Invalid e-mail address";
}}}}

function checkParticipantsField(sFieldId, sAlertId) {
 document.getElementById(sAlertId).innerHTML = "";
 sFieldContent = document.getElementById(sFieldId).value;
 sRegx = /^ *$/;
 iPos = sFieldContent.search(sRegx);
 if (iPos > -1) {
  bFormCorrect = false;
  document.getElementById(sAlertId).innerHTML = "Required information";
 }
 else {
  sRegx = /^[0-9]+$/;
  iPos = sFieldContent.search(sRegx);
  if (iPos == -1) {
   bFormCorrect = false;
   document.getElementById(sAlertId).innerHTML = "Please write digits only";
  }
  else {
   sRegx = /^0$/;
   iPos = sFieldContent.search(sRegx);
   if (iPos > -1) {
    bFormCorrect = false;
    document.getElementById(sAlertId).innerHTML = "Must be greater than 0";
}}}}

function checkForm() {
 bFormCorrect = true;
 checkField("firstName", "firstNameAlert");
 checkField("lastName", "lastNameAlert");
 checkField("title", "titleAlert");
 checkField("institution", "institutionAlert");
 checkPhoneFields("area", "exchange", "phone", "phoneAlert");
 checkEmailField("email", "emailAlert");
 checkParticipantsField("participants", "participantsAlert");
 if (!bFormCorrect) return false;
}