PerformanceObserver and timing APIs
Comes up in: Web fundamentals
This concept is being written. It gets the full five steps — explanation, predict, interview angle, practice with tests, and review cards. Here is exactly what it will cover, so you can study it elsewhere in the meantime.
What it covers
- entry types (navigation, resource, paint, largest-contentful-paint, layout-shift, event, long-animation-frame)
performance.mark/measurebuffered: true
Words you will know
What you will practise
- log LCP and INP candidates
Interview questions this answers
- How do you measure a custom performance metric in the browser?