SO-73011040

by David Thomas

HTML

<div class="form-group row">
  <div class="col-sm-6">
    <input type="float" class="form-control form-control-user" id="BMS_qty" name="BMS_qty" placeholder="BMS Quantity">
    <input type="float" class="form-control form-control-user" id="BMS_price" name="BMS_price" placeholder="BMS Price">
  </div>
</div>

<div class="col-sm-6 form-check">
  <input type="checkbox" id="tax" name="taxamount" value="0.17">
  <label for="tax">Included Tax</label><br>

  <label for="total_expenses1" style="text-align: right;">Total:- </label>
  <span id="total_expenses1"></span>
</div>

JavaScript

$('input').on('input', function() { // run anytime the value changes
  const BMS_qty = parseInt($('#BMS_qty').val(), 10),
    BMS_price = parseFloat($('#BMS_price').val()),
    tax = $('#tax').is(':checked') ? 0.17 : 0;

  let subtotal = BMS_qty * BMS_price,
    total = tax * subtotal;
  $('#total_expenses1').html(total + subtotal); // add them and output it

  // add them and output it
});