Interview Q&A / React

1. What does it mean for a React component to be pure?

   A pure component returns the same JSX for the same props, state and context, and changes nothing outside itself while rendering. Purity lets React re-run, skip or repeat renders safely, including in Strict Mode.

   IntermediateQuick answer1 min read
2. Why must a reducer function be pure, and what breaks if it is not?

   React may call a reducer more than once with the same inputs, for example in Strict Mode. A pure reducer returns a new state from state and action only. Mutating state or running side effects inside it gives wrong or duplicated results.

   IntermediateQuick answer1 min read