<script type="text/javascript" src="//code.jquery.com/jquery-1.10.2.js"></script> <script type="text/javascript"> function sum() { var txtFirstNo = document.getElementById('txtFirstNo').value; var txtSecondNo = document.getElementById('txtSecondNo').value; var result = parseInt(txtFirstNo) + parseInt(txtSecondNo); if (!isNaN(result)) { document.getElementById('txtResult').value = result; } } </script>
<div style="border:1px solid gray;width: 450px; height:300px"> <h2>Add two textbox values without pressing anybuttons</h2> <input type="text" id="txtFirstNo" placeholder="pleaseenterFirst Number" onkeyup="sum()" /> <input type="text" id="txtSecondNo" placeholder="pleaseenterSecond Number" onkeyup="sum()" /> <br /> <div style="padding-top:10px"> Result: <input type="text" id="txtResult" /> </div></div>