get value from input box and display in another input using jquery

// First way to get a value
value = $("#txt_name").val(); 

// Second way to get a value
value = $("#txt_name").attr('value');

If you want to use straight JavaScript to get the value, here is how:

document.getElementById('txt_name').value 

 so here it is


 <input id="totalsum" type="text" name="totalsum" value="<?php echo $total; ?>">
  <input id="totalsum1" type="text" name="totalsum" value="">

 <style>
 #totalsum {
    width: 110px;
    background-color: none;
    border:none;
}
</style>
<script type="text/javascript">
        $(document).ready(function() {
        $(':checkbox:checked').prop('checked',false);
    function updateSum() {
      var total = <?php echo $total; ?>;
      $(".sum:checked").each(function(i, n) {total += parseFloat($(n).val());})
      $("#totalsum").val(total.toFixed(2));
      getsum=document.getElementById('totalsum').value;
    document.getElementById('totalsum1').value =getsum;
    }
    // run the update on every checkbox change and on startup
    $("input.sum").change(updateSum);
    updateSum();
   
})
    </script>
<input name="addons1[]" class="sum" value="10.98"  type="checkbox"> Outside Wash
<br>

<input name="addons1[]"  class="sum" value="39.98"  type="checkbox"> A <br>

<input name="addons1[]"  class="sum" value="0" type="checkbox"> B <br>

<input name="addons1[]"  class="sum" value="109.78" type="checkbox"> C <br/> 

                <input id="totalasum" type="text"  value="">