React Native Threads Async Performance Promise Congestion React Native Interview 9 4

Summary

Your JavaScript never touches the screen directly. So how does a set timeout with zero milliseconds doesn't run immediately. And a login, then profile, then posts flow can't run in parallel. Close the app, reopen it, and the user is still logged in, still in dark mode. Something saved that data on the device. Takeaway: ... Every unit test passes, and the login flow is still broken. Only a test that drives the real app, a real user, catches that. One call stack, one thing at a time. Yet network requests, timers, and taps all get handled without freezing the screen. Takeaway: ... Three API calls one after another take three times as long. Run them together and you only wait A home screen needs the profile, notifications, and settings. None depend on each other, so why wait