An article on Interaction to Next Paint (INP) could begin by introducing it as a new Core Web Vital that measures a website’s responsiveness. Responsiveness refers to a page’s ability to react to user interactions and provide visual feedback quickly. This is a crucial aspect of a good user experience.
What Exactly Is INP?
The core of the article should be a detailed explanation of INP. Define it as a metric that assesses a page’s overall responsiveness throughout its entire lifecycle. INP measures the time from when a user starts an interaction (e.g., a click, tap, or keypress) until the next frame is painted to the screen. The final INP value for a page is the longest interaction that occurred, though outliers are ignored.
The Three Components of INP
Break down the INP measurement into its three key parts:
- Input Delay: The time from the start of the interaction until the event callback begins to run. This delay is often caused by the main thread being busy with other tasks.
- Processing Time: The time it takes for the event callbacks to run. It’s the work the browser does in response to the user’s action.
- Presentation Delay: The time from when the event callbacks finish until the browser can paint the next visual update on the screen.
Why Is INP Important?
Discuss the significance of INP. Explain that it provides a more holistic view of responsiveness compared to its predecessor, First Input Delay (FID), which only measured the input delay of the first interaction. A low INP score (typically less than 200 milliseconds) indicates a responsive website. In contrast, a high score suggests a poor user experience, as users may feel the page is sluggish or broken. Emphasise that a good INP score can improve a site’s search engine ranking and user satisfaction.
How to Improve INP
Conclude the article with actionable advice for developers. Suggest various optimization techniques, such as:
- Minimising JavaScript execution time by breaking up long tasks.
- Prioritising critical functions on the main thread.
- Optimising event handlers to make them run more efficiently.
- Using web workers to offload heavy computations from the main thread.
- Reducing the complexity of CSS and DOM updates.
In conclusion, Interaction to Next Paint (INP) is more than just a new metric; it’s a fundamental shift in how we measure a website’s responsiveness. By focusing on the entire lifecycle of an interaction—from user input to visual feedback—INP provides a more accurate and comprehensive picture of a user’s experience. A low INP score isn’t just about technical performance; it’s a reflection of a smooth, engaging, and trustworthy user experience. Prioritising INP optimisation is key to ensuring your site remains fast, usable, and competitive in the modern digital landscape.
