Measure App Performance with Ease: A Practical Guide to Performance API

Unlock the Power of Client-Side Performance Monitoring

For a long time, we’ve struggled to get accurate performance metrics on the client-side. Limited information and restrictive API browsers have hindered our ability to measure performance effectively. However, with the advent of new performance-oriented APIs, this is changing rapidly. The browser’s Performance API now provides us with the tools to accurately measure the performance of web pages.

Why You Should Be Using Performance API

The Performance API offers several benefits, including:

• Enhanced experience with performance profiling in dev tools
• Real user measurement (RUM) in production, going beyond what Chrome dev tools and Lighthouse can offer
• Precise timestamps, making analysis of performance metrics highly accurate

Demystifying Performance API

The Performance API can be overwhelming, with terms like High Resolution Time, Performance Timeline API, and more. Let’s break down these terms to understand what they mean and how they can be used to measure web performance.

High Resolution Time

A high resolution time is precise up to fractions of a millisecond, making it ideal for accurate measurements. This precision is achieved by using a global clock created by the User-Agent (UA), which doesn’t change with system time changes.

Performance Timeline API

The Performance Timeline API is an extension of the Performance API, providing interfaces to retrieve performance metrics based on specific filter criteria. It includes methods like getEntries(), getEntriesByName(), and getEntriesByType(), which return lists of performance entries gathered from other Performance API extensions.

Measuring Performance with Performance API

With the Performance API, we can measure various aspects of web performance, including:

• Navigation timing: Measure DNS time, request and response timings, and HTTP header size
• Resource timing: Measure load time of resources, including images, scripts, and CSS files
• Paint timing: Measure “First Time to Paint” and “First Contentful Paint”
• User timing: Measure performance for scripts, JavaScript tasks, and user interactions

Practical Applications of Performance API

Using the Performance API, we can:

• Get metrics for a single resource using getEntriesByName
• Measure document processing metrics like domInteractive, domContentLoadedEventStart, and domComplete
• Use React’s useEffect to optimize application performance

Taking it to the Next Level with Puppeteer

Puppeteer, a headless Node library, can be used in conjunction with the Performance API to extract timing metrics. This powerful combination allows us to automate performance testing and analysis.

Getting Started with LogRocket

To start using the Performance API and LogRocket, simply sign up for an app ID, install LogRocket via npm or script tag, and initialize it client-side. You can also explore additional plugins for deeper integrations with your stack.

By leveraging the Performance API and LogRocket, you can unlock the full potential of client-side performance monitoring and create better digital experiences for your users.