When should I use an Inline script and when to use external JavaScript file?

To enhance performance, try to keep JavaScript external. The separate code makes it easier for web browsers to cache. However, use inline scripts only when you’re making single page websites.

Still, it's better to use external code i.e. external JavaScript. To place JavaScript in external file create an external JavaScript file with the extension .js. After creating, add it to the HTML file in the script tag. The src attribute is used to include that external JavaScript file.

If you have more than one external JavaScript file, then add it to the same web page to increase the performance of the page.

Let’s say the following new.js is our external JavaScript file −

function display() {
   alert("Hello World!");
}

Now add the external JavaScript file to the HTML web page

Example

Live Demo

<html>
   <body>
   <form>
      <input type = "button" value = "Result" onclick = "display()"/>
   </form>

   <script src = "new.js">
   </script>
   </body>
</html>