Frontend Engineering

Frameworks (React / Vue / Angular)

6 practice questions. Free questions open a full answer guide; the rest unlock with Pro.

  • When you render a list of items in React, why does each one need a key prop, and what can go wrong if you use the array index as the key? Junior level
  • Your team is migrating a React app to a framework that defaults to React Server Components, and a teammate wants to add 'use client' to most components to keep the patterns everyone already knows. How would you reason about where the server/client boundary should sit?Go Pro Senior level
  • What's the difference between a controlled and an uncontrolled form input in React, and how do you decide which to use?Go Pro Junior level
  • How do you decide whether a piece of UI should be a server component or a client component in a React Server Components setup, and what goes wrong if you get that boundary wrong?Go Pro Mid level
  • A teammate argues your interactive content site should stay a single-page React app because 'it's all React anyway,' while you think an islands or server-first architecture would serve users better. How do you frame that trade-off?Go Pro Senior level
  • Walk me through how a virtual-DOM framework like React decides what to re-render when state changes, and what the signals-based approach in Vue or Solid does differently.Go Pro Mid level
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