The script does not work after loading the page with AJAX

Zdraste, there is a file index.php, in it when you click on the button another file is included (include) in which there is a field (input). When the key is released, the script should work, but this does not happen. I tried to solve the problem using "on" and so on. But it does not work.

$('.input').on('keyup', function(){ var value = $('.input').val(); alert(value); }); 

Self input

  echo '<input type="number" class="input" min="1" max="99999" name="price" value="1"><br />';