Neopitniy

$connect = mysqli_connect("localhost", "root", "", "site");

$sql = "SELECT * FROM `users` WHERE `login` = ?";
$stmt = $connect ->prepare($sql);
$stmt->bind_param("s", $_POST['username']);
$stmt->execute();
$stmt->store_result();

if ($stmt->num_rows > 0) {
    echo 'This username is already taken';
} else {
    echo 'This username is available';
}

preg_match_all('~(?<=<p>).+?(?=</p>)~', $str, $match);

$data = array_map(function($n) {
  return explode('-', $n, 2);
}, $match[0]);

$result = [];
if(...) {
     foreach(... as ...) {
          $images = $this->model_catalog_product->getProductImages($result['product_id']);
          if(isset($images[0]['image']) && !empty($images)){
               $images = $images[0]['image']; 
          } else {
               $images = $image;
          }
}

<picture>
 <source srcset="mdn-logo-wide.png" media="(min-width: 600px)">
 <img src="mdn-logo-narrow.png" alt="MDN">
</picture>

var info = false;

$("#start").click(function(){
if(!info){
  $.getJSON( "/json.php", function( data ) {
    console.log(data);
info = data;
  });
}
});

Можно ли назначать id, class для section?