How do get change value of <input> element?

I have a input in datalist

<input type="text" value="1" id="txtcount">
 

I want get new value of it when text change.

I use this code but don't work for me .

<script>
 //look no global needed:)
 
 $(document).ready(function(){
     // Get the initial value
    var $el = $('#txtcount');
    $el.data('oldVal',  $el.val() );
 
 
    $el.change(function(){
         //store new value
         var $this = $(this);
         var newValue = $this.data('newVal', $this.val());
    })
    .focus(function(){
         // Get the value when input gains focus
         var oldValue = $(this).data('oldVal');
    });
 });
 

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