RCT.05.03 Mid-level

Other React 19 changes

Comes up in: React, Recruiter screen

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

ref as prop
ref cleanup
document metadata (<title>, <meta>, <link> in components)
stylesheet precedence
resource preloading APIs (preload, preinit)
better hydration errors
custom elements support
removed legacy APIs (propTypes checks, string refs, ReactDOM.render)
what 19.1/19.2/19.3 added (facts)

Words you will know

hydrationresource preloading

What you will practise

migrate a React 18 component to 19 idioms

Interview questions this answers

What changed between React 18 and React 19?