Use Async Loading for JavaScript Modules to Prevent Render Blocking

Performance Analyzer

What is this warning?

A JavaScript module on your page is loading synchronously, which can block the rendering of your page. Modern JavaScript modules should be loaded asynchronously to prevent them from delaying the display of content to users.

How to Fix This Issue

How to Fix It

The Problem

<script type="module" src="/js/app.js"></script>

The Solution

Add the `async` attribute to module scripts to prevent them from blocking page rendering.

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

Why This Works

Async loading allows the browser to continue parsing and rendering the page while the module downloads and executes, leading to faster perceived performance and better Core Web Vitals scores.

SEO Impact

This issue can affect your site's search engine rankings and user experience. Addressing it promptly helps ensure optimal performance and visibility in search results.

Automatic Detection

Black SEO Analyzer automatically checks for this warning during site analysis, along with hundreds of other technical SEO issues.

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