Fire oninput event with jQuery

Use .on('input'). For example:

$('textarea').on('input', function() {
  text = $('textarea').val();
  $('div').html(text);
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<textarea placeholder="Type something here"></textarea>
<div></div>