Performance Monitoring

There are 2 main schools of thought when it comes to performance monitoring:

• Controlled monitoring

  • Doing things like using Lighthouse, throttling CPU/internet speeds, etc.

  • At the end of the day though, you're in a controlled space

• User monitoring

  • You send code into production, and when your users download it, it measures performance and sends it back to you

Performance API

A common way to perform user monitoring is through the Performance API.

performance.mark('start');

// Do some work...

performance.mark('end');

performance.measure('Our measurement', 'start', 'end');
performance.getEntriesByType('measure');

// POST request to send data to...

Note: When you use the Performance API, Chrome dev tools adds a "Timings" area in your Performance profiles, allowing you to see your custom user timings.