---
title: "Optimize JavaScript Module Loading | bseoa"
description: "You're using a modern JavaScript module, but you haven't specified how it should load. By default, modules are deferred, but it's a good practice to be explici…"
image: "https://www.blackseoanalyzer.com/static/images/black-seo-analyzer-og-image.png"
canonical: "https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/module-without-async"
language: "en"
---

# Optimize JavaScript Module Loading

JavaScript Analyzer

## What is this warning?

You're using a modern JavaScript module, but you haven't specified how it should load. By default, modules are deferred, but it's a good practice to be explicit. If the module can run independently, adding the `async` attribute can sometimes improve performance by allowing it to execute sooner.

## How to Fix This Issue

### How to Fix It

#### The Problem

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

#### The Solution

If the module doesn't depend on other scripts and its execution order isn't critical, add the `async` attribute to it.

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

#### Why This Works

While modules are deferred by default, explicitly adding `async` can allow the browser to execute the script as soon as it's downloaded (if the main thread is free), which can be faster than waiting for the entire document to be parsed.

### 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

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

## Other JavaScript Analyzer issues

- [Add crossorigin Attribute for Better Error Logging](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/missing-crossorigin-attribute)
- [Audit Third-Party Scripts for Performance and Security](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/third-party-script-loaded)
- [Avoid document.write for Better Performance and Security](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/document-write-usage)
- [Avoid eval() Due to Significant Security Risks](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/eval-usage)
- [Avoid Synchronous Scripts in <head> to Speed Up Rendering](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/synchronous-script-in-head)
- [Clarify Script Loading by Removing Redundant async and defer](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/redundant-async-and-defer)
- [Correct Unknown Script type for Proper Execution](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/unknown-script-type)
- [Deprecated JavaScript APIs: document.write, escape() and Inline Handlers](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/deprecated-api-usage)
- [Enhance Security by Loading All Scripts Over HTTPS](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/insecure-script-load)
- [Improve Code Maintainability by Avoiding Inline Event Handlers](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/inline-event-handler)
- [Improve Performance by Externalizing Large Inline Scripts](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/large-inline-script)
- [Improve Security with Subresource Integrity (SRI) for CDN Scripts](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/missing-integrity-attribute)
- [Modernize Your HTML by Removing Unnecessary Script type Attributes](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/unnecessary-type-attribute)
- [Optimize Loading of Blocking Third-Party Scripts](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/blocking-third-party-script)
- [Optimize Script Loading to Prevent Page Rendering Delays](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/render-blocking-script)
- [Preload Critical Scripts to Improve Page Load Performance](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/missing-preload-hint-for-script)
- [Remove console.log Statements from Production Code](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/console-log-usage)

## Ready to Unlock Your Site's Full SEO Potential?

Choose the license that fits your needs and start getting the deep, actionable insights you deserve.

[Download Free Trial](https://www.blackseoanalyzer.com/en/free-trial) [Purchase Single License](https://www.blackseoanalyzer.com/buy/single)

```json
{"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://www.blackseoanalyzer.com/#organization","name":"Fiscus Technology, LLC","url":"https://www.blackseoanalyzer.com/","logo":"https://www.blackseoanalyzer.com/static/images/black-seo-analyzer.png","founder":{"@type":"Person","name":"Seth Black"}},{"@type":"WebSite","@id":"https://www.blackseoanalyzer.com/#website","name":"bseoa","url":"https://www.blackseoanalyzer.com/","publisher":{"@id":"https://www.blackseoanalyzer.com/#organization"}},{"@type":"TechArticle","@id":"https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/module-without-async#article","headline":"Optimize JavaScript Module Loading","name":"Optimize JavaScript Module Loading","description":"You're using a modern JavaScript module, but you haven't specified how it should load. By default, modules are deferred, but it's a good practice to be explicit. If the module can run independently, adding the async attribute can sometimes improve performance by allowing it to execute sooner.","url":"https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/module-without-async","image":{"@type":"ImageObject","url":"https://www.blackseoanalyzer.com/static/images/black-seo-analyzer-og-image.png","width":1200,"height":630},"author":{"@type":"Person","name":"Seth Black","url":"https://www.blackseoanalyzer.com/about"},"publisher":{"@id":"https://www.blackseoanalyzer.com/#organization"},"mainEntityOfPage":{"@type":"WebPage","@id":"https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/module-without-async"},"inLanguage":"en-US","keywords":"technical SEO, SEO warning, Seth Black&#39;s SEO Analyzer"},{"@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://www.blackseoanalyzer.com/"},{"@type":"ListItem","position":2,"name":"Technical SEO Warnings","item":"https://www.blackseoanalyzer.com/en/technical-seo"},{"@type":"ListItem","position":3,"name":"Optimize JavaScript Module Loading","item":"https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/module-without-async"}]}]}
```