I'm not sure exactly what your problem is, but you can try the following:
<html>
<head>
<script type = "text/javascript">
functionmyfunction() {
alert("how are you");
}
</script>
</head>
<body>
<p>Click the following button to see the function in action</p>
<input type = "button" onclick = "myfunction()" value = "Display">
</body>
</html>
It will be create and define a function in the HTML document's head section. To invoke this function in the html document, I have to create a simple button and using the onclick event attribute (which is an event handler) along with it,I can call the function by clicking on the button
driving directions.