onkeyup javascript same text feild operation like sum ,sub,multiple,division

<div>
 
   <label>
                    <span>current weight per bag</span>
                    <input  type="text"  name="cwpbags" id="nos" onKeyUp="sum1();"   autofocus>
                    <script> function sum1() {
            var txtFirstNumberValue = document.getElementById('nos').value;
          
             var txtthirdNumberValue = document.getElementById('bag').value;
              var txtthirddNumberValue = document.getElementById('loading').value;
             var initial =1000;
            var result = parseFloat(txtFirstNumberValue)  * parseFloat(txtthirdNumberValue) * parseFloat(txtthirddNumberValue) ;
            var div = parseFloat(txtFirstNumberValue)  * parseFloat(txtthirdNumberValue) / initial;
            if (!isNaN(result)) {
                document.getElementById('amount').value = result;
            };
            if (!isNaN(div)) {
                document.getElementById('freight').value = div;
            };
        }</script>
                </label>
               
                <label>
                    <span>current No of bag</span>
                    <input  type="text"  name="cnofbags" id="bag"  onkeyup="sum1();"  autofocus>
                </label>
            </div>
            <div>
                <label>
                    <span>loading</span>
                    <input  type="text"  name="loading" id="loading"  onKeyUp="sum1();"  autofocus>
                </label>
            </div><div>
                <label>
                    <span>amount</span>
                    <input  type="text"  name="amount" id="amount"  required autofocus>
                </label>
            </div>
            <div>
                <label>
                    <span>HOW many tons</span>
                    <input  type="text"  name="loading" id="freight"   autofocus>
                </label>
            </div>

DEMO:

current weight per bag current No of bag

loading

amount

HOW many tons

second Highest value get database

SELECT totalprice FROM raw_arrivepurchase WHERE totalprice = (SELECT MAX(totalprice) FROM raw_arrivepurchase WHERE totalprice < (SELECT MAX(totalprice) FROM raw_arrivepurchase))