perhitungan automatis dengan HTML dan JavaScript

<html>
<head>
 </head>
<body>
<h3>Membuat Penjumlahan Otomatis</h3>
<input type="text" id="txt1"  onkeyup="sum();" />
<input type="text" id="txt2"  onkeyup="sum();" />=
<input type="text" id="txt3" />
</body>
</html>
<script>
function sum() {
      var txtFirstNumberValue = document.getElementById('txt1').value;
      var txtSecondNumberValue = document.getElementById('txt2').value;
      var result = parseInt(txtFirstNumberValue) + parseInt(txtSecondNumberValue);
      if (!isNaN(result)) {
         document.getElementById('txt3').value = result;
      }
}
</script>

Komentar