Andrew

let frm = document.querySelector('.frm'); // .frm = класс формы
    frm.addEventListener('submit', function(e){
        e.preventDefault();
        return checkCaptcha();
    });

function massive_csv($file_name){
$arr = file('./' . $file_name . '.csv'){

var radios = $('input[type=radio]');
radios.on('click', function(){radios.removeClass('SomeClass');$(this).addClass('SomeClass')});

$value = '4..6';

$j = explode('..', $value);

$result = [];

while((int) $j[0] <= (int) $j[1]){
    $result[] = $j[0]++;
}
print_r($result); // Array ( [0] => 4 [1] => 5 [2] => 6 )

<script type="text/javascript" charset="utf-8">
$(function(){
  $("select#city").change(function(){
    $.getJSON("/select.php",{id: $(this).val(), ajax: 'true'}, function(j){
      var options = '';
      for (var i = 0; i < j.length; i++) {
        options += '<option value="' + j[i].optionValue + '">' + j[i].optionDisplay + '</option>';
      }
      $("select#myselect").html(options);
    })
  })
})
</script>

$(window).on('scroll', function(){
    if($(window).scrollTop() >= $('.element').offset().top){
      $('body').addClass('new-class');
    }
  });