JavaScript alert box
<html><head>
<script type="text/javascript">
function show_alert()
{
alert("I am an alert box!");
}
</script>
</head>
<body>
<input type="button" onClick="show_alert()" value="Show alert box" />
</body>
</html>
<script type="text/javascript">
function show_alert()
{
alert("I am an alert box!");
}
</script>
</head>
<body>
<input type="button" onClick="show_alert()" value="Show alert box" />
</body>
</html>
Result
