System Design · Middle · Question 29 of 75

How do you track performance for real users?

Explanation

The web-vitals library (or useReportWebVitals in Next.js) sends LCP, INP, CLS via sendBeacon. Look at the 75th percentile by device type and page, and correlate regressions with releases. Lab tests are useful but don't replace field data.

Further reading

Problem with a question

System Design · Middle · question 29

Test yourself

Take the System Design · Middle quiz: questions and options are shuffled, and you get a review of your mistakes at the end.

Take this quiz