CWV Mobile Optimization Deferring Third-Party Scripts In AEM For Improved Performance

Hey guys! Today, we're diving deep into a crucial aspect of web performance optimization, especially for mobile users: Core Web Vitals (CWV). We'll be focusing on a specific strategy to improve your website's Interactivity to Next Paint (INP) score by strategically delaying third-party scripts. This approach, particularly relevant for sites built on platforms like AEM, can significantly enhance user experience by ensuring faster page load times and improved responsiveness.

Understanding the CWV Performance Issue

So, what's the big deal with Core Web Vitals? Well, these metrics are Google's way of measuring how users experience your website. They're crucial for SEO and, more importantly, for keeping your visitors happy. One of the key metrics is Interactivity to Next Paint (INP), which measures how quickly your site responds to user interactions. A high INP score means a sluggish website, which can drive users away. In this particular case, we're tackling an INP issue on the mobile version of https://main--bbird--aemsites.aem.page/, where third-party scripts are the culprits.

The Problem: Third-Party Scripts Delaying Page Load and Interaction

Third-party scripts, such as auth0-spa-js.production.js, are often necessary for website functionality – things like analytics, advertising, and social media integrations. However, these scripts can be resource-intensive and often delay page load and interaction responsiveness. When these scripts load and execute, they can block the main thread of the browser, preventing it from handling user interactions quickly. This leads to a frustrating experience, especially on mobile devices with limited processing power and network bandwidth. Identifying and optimizing these scripts is crucial for improving your website's performance and, in turn, user satisfaction.

Why Mobile Performance Matters More Than Ever

With the majority of web traffic now originating from mobile devices, optimizing for mobile is no longer optional – it's a necessity. Mobile users expect fast, seamless experiences, and a slow-loading website can lead to high bounce rates and lost opportunities. Google also prioritizes mobile-friendliness in its search rankings, making mobile performance a critical factor for SEO. Therefore, focusing on mobile CWV metrics like INP is essential for ensuring your website meets the demands of today's users.

Expected Impact: A 100ms Improvement – Why It Matters

You might be thinking, "100 milliseconds? Is that even noticeable?" The answer is a resounding yes! In web performance, every millisecond counts. A 100ms improvement in INP can translate to a noticeable difference in how responsive your website feels. It can be the difference between a user clicking a button and instantly seeing a response, or experiencing a frustrating delay. These small improvements add up to a significantly better overall user experience, leading to increased engagement, conversions, and customer satisfaction.

The Solution: Deferring Third-Party Scripts to the "loadDelayed" Phase

Okay, so we know the problem – third-party scripts are slowing things down. What's the solution? The strategy we're focusing on is deferring the loading of these scripts to a later phase, specifically the "loadDelayed" phase. This means that instead of loading these scripts immediately when the page loads, we'll wait until after the initial page content has rendered and the user has started interacting with the site.

What is the "loadDelayed" Phase?

The "loadDelayed" phase is a strategy for prioritizing the loading of critical resources first and delaying the loading of less critical resources until later. In this case, we're identifying third-party scripts as less critical for the initial user experience and deferring their loading. This allows the browser to focus on rendering the main content of the page and responding to user interactions without being bogged down by these scripts.

How Deferring Scripts Improves INP

By deferring the loading of third-party scripts, we're freeing up the main thread of the browser to handle user interactions more quickly. This directly translates to a lower INP score. When a user clicks a button, submits a form, or performs any other action, the browser can respond almost immediately, creating a smoother and more responsive experience. This is especially important for interactive elements on your website, such as navigation menus, search bars, and forms.

Which Scripts to Defer? The Case of auth0-spa-js.production.js

In this specific scenario, the script we're targeting is auth0-spa-js.production.js. This script is likely related to authentication functionality, which is important but not necessarily critical for the initial page load. By deferring this script, we can improve the perceived performance of the website without sacrificing its core functionality. However, it's important to carefully consider which scripts to defer, as deferring essential scripts can break your website or negatively impact the user experience.

AEM-Specific Implementation Guide: Getting Your Hands Dirty

Now, let's get practical. How do we actually implement this script deferral strategy, especially within the context of Adobe Experience Manager (AEM)? AEM is a powerful platform, but it requires a specific approach to optimization. Here's a guide to help you through the process.

File Locations to Check: Where the Magic Happens

The first step is to identify the files where these scripts are being included. This often involves checking the following locations within your AEM project:

• Client Libraries (ClientLibs): AEM ClientLibs are the primary mechanism for managing CSS and JavaScript resources. Look for ClientLibs that include the auth0-spa-js.production.js script or any related third-party scripts. These libraries are typically located under /apps/<your-project>/clientlibs.
• Templates and Components: Check your page templates and components to see if the scripts are being included directly in the HTML. This is less common but still a possibility, especially if you have custom components.
• Global JavaScript Files: Some AEM projects may have global JavaScript files that are included on every page. These files are often located in the /etc folder or within your project's ClientLibs.

Identifying the Inclusion Method: How are the Scripts Being Added?

Once you've located the files, you need to determine how the scripts are being included. There are several common methods:

• <script> Tags: The most straightforward method is using <script> tags directly in the HTML. If you see these, you can modify the tags to defer the script loading.
• AEM ClientLib Tags: AEM provides special tags for including ClientLibs, such as <cq:includeClientLib>. These tags allow you to manage dependencies and optimize the loading order of your resources.
• JavaScript Code: In some cases, scripts may be added dynamically using JavaScript code. This is a more complex scenario that may require refactoring the code.

Modifying ClientLibs for Deferred Loading: The Key to Optimization

The most common and recommended approach for deferring scripts in AEM is to modify the ClientLibs. Here's how you can do it:

1. Create a New ClientLib Category: If you don't already have one, create a new ClientLib category specifically for deferred scripts. This helps you keep your code organized and makes it easier to manage these scripts in the future.
2. Move the Scripts: Move the auth0-spa-js.production.js script (and any related third-party scripts) to the new ClientLib category.
3. Add the defer Attribute: When including the ClientLib in your page template or component, add the defer attribute to the <script> tag. This tells the browser to download the script in the background and execute it after the HTML has been parsed.
4. Implement LoadDelayed Logic: To fully implement the "loadDelayed" phase, you'll need to add JavaScript code that listens for user interaction events (e.g., clicks, scrolls, key presses). Once these events have occurred, you can then load the deferred ClientLib dynamically using the CQ.utils.loadClient библиотеки method. This ensures that the scripts are only loaded when they're actually needed.

Example Code Snippet (JavaScript):

function loadDelayedScripts() {
 // Load the deferred ClientLib
 CQ.utils.loadClient библиотеки('your.deferred.clientlib');
 // Remove the event listeners
 document.removeEventListener('click', loadDelayedScripts);
 document.removeEventListener('scroll', loadDelayedScripts);
}

// Listen for user interaction events
document.addEventListener('click', loadDelayedScripts);
document.addEventListener('scroll', loadDelayedScripts);

Testing and Verification: Ensuring Success

After implementing the changes, it's crucial to test and verify that the script deferral is working as expected. Here are some key steps:

• Use Browser Developer Tools: Use the browser's developer tools (e.g., Chrome DevTools) to inspect the network activity and confirm that the scripts are being loaded after the initial page load.
• Measure INP: Use tools like Google PageSpeed Insights or WebPageTest to measure the INP score before and after the changes. You should see a noticeable improvement.
• Test on Mobile Devices: Test the website on actual mobile devices to ensure that the changes are effective in a real-world environment.
• Check for Functionality Issues: Carefully check your website's functionality to ensure that deferring the scripts hasn't broken anything. Pay close attention to features that rely on the deferred scripts, such as authentication and user interactions.

Performance Target: Aiming for Excellence

Let's talk about the specific performance target we're aiming for. As mentioned earlier, the goal is to achieve a ~100ms improvement in INP on mobile devices. This is a significant improvement that can have a tangible impact on user experience. However, it's important to remember that this is just a starting point. The ideal INP score is 200 milliseconds or less, so you should always strive to improve your website's performance further.

Why INP Matters: A Quick Recap

INP is a crucial metric because it directly reflects how responsive your website feels to users. A low INP score means that your website is quick to respond to user interactions, creating a smooth and enjoyable experience. A high INP score, on the other hand, indicates that your website is sluggish and unresponsive, which can lead to frustration and abandonment.

Mobile Focus: Prioritizing the Mobile Experience

As we've discussed, mobile performance is paramount in today's web landscape. Therefore, the primary focus of this optimization effort is on mobile devices. This doesn't mean that desktop performance isn't important, but mobile users often have slower connections and less powerful devices, making mobile optimization a critical priority.

Continuous Improvement: The Journey Never Ends

Optimizing web performance is an ongoing process. The web is constantly evolving, and new technologies and techniques are emerging all the time. Therefore, it's essential to continuously monitor your website's performance and look for opportunities to improve. Regularly measure your CWV metrics, identify areas for optimization, and implement changes. This iterative approach will help you ensure that your website remains fast, responsive, and user-friendly.

Conclusion: A Faster Website for Happier Users

By strategically deferring third-party scripts, we can significantly improve website performance, especially on mobile devices. This translates to a better user experience, increased engagement, and improved business outcomes. So, let's get those scripts deferred and make the web a faster place, one website at a time! Remember, guys, every millisecond counts! This optimization strategy, particularly within the AEM ecosystem, empowers you to deliver seamless experiences and keep your users happy and engaged. Happy optimizing!