<!DOCTYPE html>
<html>
<head>
<title>encode and decode</title>
<script type="text/javascript" >
function validation() {
var val = document.getElementById('in');
if (val.value.length == 0) {
alert("Required");
}
}
</script>
</head>
<body>
<h1>Example of required field validation control</h1>
<input type="text" name="gt" value="" id="in" />
<button onclick="validation();">perform validation</button>
</body>
</html>
<html>
<head>
<title>encode and decode</title>
<script type="text/javascript" >
function validation() {
var val = document.getElementById('in');
if (val.value.length == 0) {
alert("Required");
}
}
</script>
</head>
<body>
<h1>Example of required field validation control</h1>
<input type="text" name="gt" value="" id="in" />
<button onclick="validation();">perform validation</button>
</body>
</html>
Code generate the following output
