<html> <head> <script type="text/javascript"> function myfunction() { alert("HELLO") } </script> </head> <body> <?php $txt="Hello World"; echo $txt; ?> <form> <input type="button" onclick="myfunction()" value="Call function"> </form> <p>By pressing the button, a function will be called. The function will alert a message.</p> </body> </html>