Here i will show you how to use JavaScript on HTML page.JavaScript code can be inserted either in the head of the document (between the <head> and </head> tags) or in the body (between the <body> and </body> tags). However, it is a good idea to always place JavaScript code in the head if you can.
Example
<html>
<head>
<title>My Page</title>
<script language="javascript" type="text/javascript">
function myFunction() {
alert('Hello world');
}
</script>
</head>
<body>
<a href="javascript:myFunction();">Click here</a>
</body>
</html>
Since the head loads before the body, placing code in the head
ensures that it is available when needed. For example, the following
code will work once the page has completely loaded, but if a user
manages to click the link before the function has loaded they will get
an error. This can easily become an issue if the page is large or slow
to load.
Example
<html>
<head><title>My Page</title>
</head>
<body>
<a href="javascript:myFunction();">Click here</a>
<script language="javascript" type="text/javascript">
function myFunction()
{
alert('Hello world');
}
</script>
</body>
</html>
