Jquery dynamic addition/subtraction/multiplication/division of multiple text box values in popup

Answer 1

You should you document.getElementById('id').value to get value of textbox. Your code should be:

var amountfdtlspop = document.getElementById('amountfdtlspop').value;
var fineAmt = document.getElementById('fineAmt').value;
var waivedAmt = document.getElementById('waivedAmt').value;
var schShipAmt = document.getElementById('schShipAmt').value;
var grndttlAmt = document.getElementById('grndttlAmt');
grndttlAmt.value = amountfdtlspop + fineAmt + waivedAmt + schShipAmt;