sample: link between $.index and an array

HTML

<input>

<ul>
  <li>item</li>
  <li>item</li>
  <li>item</li>

</ul>

JavaScript

$('li').on('click', function() {
	var arr = ['A', 'B', 'C', 'D', 'E'];
  var index = $('li').index(this);
  $('input').val(arr[index]);
});