Defer loading/parsing of Javascript

Rule from inspect under performance category

What is a trooper!

we have submitted your edit to the community for review! We'll review and make it live on the site in the next few hours, the internet thanks you :).

Browse another section of the knowledge base



Suggest an edit

Cancel

This rule has no content... yet.

Add content to this rule

Or just browse to view rules that have content



 

By delaying when a Javascript file is loaded and parsed pages can be loaded and content shown, with the Javascript then following to provide extra functionality.

After loading, the parsing of Javascript is a heavy operation. Keeping the Javascript code of a web page small and only loading what's needed is a great way to reduce the performance hit browsers (and mostly mobile devices) take when hitting your page to render a basic layout.

How do I fix this ?

Move Javascript files to the end of your <body> tag, just before closing it </body> or mark Javascript files (that are not needed immediately to show the content of the page) with the attribute async as such:

<script src="/app.js" async></script>

Resources

Browse another section of the knowledge base



Signup icon
Ready to see how well your site scores?

Passmarked works best when you have an account. It allows you to keep a dashboard with saved data of the sites you have run through the system, we’ll alert you about important updates and you get access to the Passmarked Slack forum.

Sign up to get started