To use the same JavaScript in more than one page, add the js code in an external JavaScript file. Let’s say the following demo.js is our external JavaScript file −
function display() { alert("Hello World!"); }
Now add the external JavaScript file to the following HTML web page. In the same way, you can add it to multiple content page.
<html> <body> <form> <input type="button" value="Result" onclick="display()"/> </form> <script src="demo.js"> </script> </body> </html>