var verzonden = false;

function trim(strText) { 
  // this will get rid of leading spaces 
  while (strText.substring(0,1) == ' ') 
    strText = strText.substring(1, strText.length);

  // this will get rid of trailing spaces 
  while (strText.substring(strText.length-1,strText.length) == ' ')
    strText = strText.substring(0, strText.length-1);

  return strText;
} 

function checkSubmit() {
  if(verzonden==false) {
    verzonden=true;
    return true;
  }
  else {
    alert("\nThe form is being submitted.\n\nPlease stand by.");
    return false;
  }
}

function testForm() {

for (i=0; i<document.forms[0].length;i++) {
  if (document.forms[0].elements[i].type!="hidden") {
    document.forms[0].elements[i].value = trim(document.forms[0].elements[i].value);
  }
}

if (req_naam==true) {
  if (document.forms[0].elements["naam"].value =="") {
    alert("\nYou haven't filled in your name.\n\nPlease fill in your name.")
    document.forms[0].elements["naam"].focus();
    return false;
  }

  for (var i = 0; i < document.forms[0].elements["naam"].value.length; i++) {
    var ch = document.forms[0].elements["naam"].value.substring(i, i + 1);
    if (((ch < "a" || "z" < ch) && (ch < "A" || "Z" < ch)) && ch != '.' && ch != ' ') {
      alert("\nThe field 'name' only accepts letters.\n\nPlease fill in your name.");
      document.forms[0].elements["naam"].select();
      document.forms[0].elements["naam"].focus();
      return false;
    }
  }
}

if (req_adres==true) {
  if (document.forms[0].elements["adres"].value == "") {
    alert("\nYou haven't filled in your address.\n\nPlease fill in your address.")
    document.forms[0].elements["adres"].focus();
    return false;
  }

  for (var i = 0; i < document.forms[0].elements["adres"].value.length; i++) {
    var ch = document.forms[0].elements["adres"].value .substring(i, i + 1);
    if (((ch < "a" || "z" < ch) && (ch < "A" || "Z" < ch )) && (ch < "0" || "9" < ch) && ch != '.'  && ch != ' ') {
      alert("\nThe field 'address' only accepts letters & numbers.\n\nPlease fill in your address.");
      document.forms[0].elements["adres"].select();
      document.forms[0].elements["adres"].focus();
      return false;
    }
  }
}

if (req_postcode==true) {
  if (document.forms[0].elements["postcode"].value == "") {
    alert("\nYou didn't fill in your postal code.\n\nPlease fill it in.")
    document.forms[0].elements["postcode"].focus();
    return false;
  }

  for (var i = 0; i < document.forms[0].elements["postcode"].value.length; i++) {
    var ch = document.forms[0].elements["postcode"].value .substring(i, i + 1);
    if (((ch < "a" || "z" < ch) && (ch < "A" || "Z" < ch )) && (ch < "0" || "9" < ch) && ch != ' ') {
      alert("\nThe field 'postal code' only accepts letters and numbers.\n\nPlease fill in your postal code.");
      document.forms[0].elements["postcode"].select();
      document.forms[0].elements["postcode"].focus();
      return false;
    }
  }
}

if (req_woonplaats==true) {
  if (document.forms[0].elements["woonplaats"].value =="") {
    alert("\nYou haven't filled in your city.\n\nPlease fill in your city.")
    document.forms[0].elements["woonplaats"].focus();
    return false;
  }

  for (var i = 0; i < document.forms[0].elements["woonplaats"].value.length; i++) {
    var ch = document.forms[0].elements["woonplaats"].value.substring(i, i + 1);
    if (((ch < "a" || "z" < ch) && (ch < "A" || "Z" < ch)) && ch != ' ') {
      alert("\nThe field 'city' only accepts letters.\n\nPlease fill in your city.");
      document.forms[0].elements["woonplaats"].select();
      document.forms[0].elements["woonplaats"].focus();
      return false;
    }
  }
}

if (req_land==true) {
  if (document.forms[0].elements["land"].value =="") {
    alert("\nYou haven't filled in your country. Please fill in your country.");
    document.forms[0].elements["land"].focus();
    return false;
  }

  for (var i = 0; i < document.forms[0].elements["land"].value.length; i++) {
    var ch = document.forms[0].elements["land"].value.substring(i, i + 1);
    if (((ch < "a" || "z" < ch) && (ch < "A" || "Z" < ch)) && ch != ' ') {
      alert("\nThe field 'Country' only accepts letters. Please fill in your country.");
      document.forms[0].elements["land"].select();
      document.forms[0].elements["land"].focus();
      return false;
    }
  }
}

if (req_telefoon==true) {
  if (document.forms[0].elements["telefoon"].value =="") {
    alert("\nYou haven't filled in your telephonenumber.\n\nPlease fill in your telephonenumber.")
    document.forms[0].elements["telefoon"].focus();
    return false;
  }

  for (var i = 0; i < document.forms[0].elements["telefoon"].value.length; i++) {
    var ch = document.forms[0].elements["telefoon"].value.substring(i, i + 1);
    if (((ch < "0" || "9" < ch)) && ch != '-' && ch != ' ') {
      alert("\nThe field 'telephone' only accepts numbers.\n\nPlease fill in your telephonenumber.");
      document.forms[0].elements["telefoon"].select();
      document.forms[0].elements["telefoon"].focus();
      return false;
    }
  }
}

if (req_email==true) {
  if (document.forms[0].elements["email"].value =="") {
    alert("\nYou haven't filled in your email address.\n\nPlease fill in your email address.")
    document.forms[0].elements["email"].focus();
    return false;
  }

  var apestaart = false;
  var punt = false;
  for (var i = 0; i < document.forms[0].elements["email"].value.length; i++) {
    var ch = document.forms[0].elements["email"].value.substring(i, i + 1);
    if (!apestaart && ch=="@") { apestaart = true; }
    if (apestaart && !punt && ch==".") { punt = true; }
    if (((ch < "a" || "z" < ch) && (ch < "A" || "Z" < ch )) && (ch < "0" || "9" < ch)  && ch != '@' && ch != '-' && ch != '.' && ch != '_') {
      alert("\nThe Ffeld 'email address' only accepts letters, numbers and the characters @-._\n\nPlease fill in your email address.");
      document.forms[0].elements["email"].select();
      document.forms[0].elements["email"].focus();
      return false;
    }
  }
  if (!apestaart || !punt) {
    alert("\nThe value in the field 'email address' is not valid.\n\nPlease fill in your email address.");
    document.forms[0].elements["email"].select();
    document.forms[0].elements["email"].focus();
    return false;
  }
}

if (!checkSubmit()) { return false; }
  
return true;

}