The ever-evolving landscape of web development and user experience brings new challenges and opportunities for developers. In this fast-paced environment, the Web Vitals program plays a crucial role in helping web developers measure and improve key aspects of user experience. In a significant development, the Chrome team has decided to replace First Input Delay (FID) with Interaction to Next Paint (INP) as a Core Web Vital on March 12, 2024. This blog post aims to guide developers through this transition, offering insights from the Chrome team and providing tips on preparing for the change.

Understanding the Transition:

The need for a new metric became apparent over time as the responsiveness-focused FID had limitations in capturing all aspects of web interactivity. INP, introduced as an experimental metric in May 2022, has now undergone a journey from experimental status to pending, and finally, it will officially become a Core Web Vital.

Preparing for the Change:

1. Evaluate Your Website’s INP: Begin by assessing if your website’s INP meets the “good” threshold. Core Web Vitals are evaluated based on performance at the 75th percentile of all page loads. Utilize tools like PageSpeed Insights or consider Real User Monitoring (RUM) providers for field data.
2. Diagnose and Troubleshoot INP: If your website falls into the “needs improvement” or “poor” category, utilize available resources to diagnose and troubleshoot INP. Identify slow interactions in the field and manually diagnose potential issues in the lab.
3. Optimization Strategies: Depending on your diagnosis, employ optimization strategies:
   • Optimize long tasks, particularly if JavaScript is consuming significant main thread time.
   • Address input delay issues to enhance the responsiveness of interactions.
   • Minimize large DOMs, complex layouts, and excessive CSS selectors.
4. Case Studies and Business Outcomes: Explore case studies, such as those from The Economic Times and redBus, showcasing how reducing interaction latency positively impacts business outcomes. Optimizing INP can align with your broader goals.

Anticipating Changes:

1. INP as a Core Web Vital: On March 12, 2024, INP will officially replace FID as a Core Web Vital. FID will be deprecated and removed from the program.
2. Documentation Changes: Expect changes in FID documentation. While historical information will remain, notices emphasizing FID’s deprecated status will be added. Relevant INP documentation will be highlighted, and FID-centric documentation may be redirected.
3. Google Tools Updates: FID will be removed from Google Search Console as soon as INP becomes a Core Web Vital. Other tools, like PageSpeed Insights and CrUX, will offer a six-month deprecation period to allow developers to update their code.

Conclusion:

As INP takes center stage in Core Web Vitals, web developers must proactively adapt to these changes. By preparing, diagnosing, and optimizing for INP, developers can ensure a smooth transition, enhance user experiences, and align with the latest standards in web development. Stay informed, leverage available resources, and embrace the opportunities that come with this evolving landscape.