Learn TypeScript 3 by Building Web Applications

Function components

Idiomatic React components are written using pure functions. There are multiple reasons for this:

• Functions are simpler to write and to read/understand.
• Functions require less code than classes.
• Pure functions are stable, deterministic, predictable and have no side-effects.
• Pure functions are easily testable.

Function components are powerful enough for most use cases and should be preferred whenever possible.

In versions of React prior to 16.8 (https://reactjs.org/blog/2019/02/06/react-v16.8.0.html), class components were needed to be able to use features such as component state, lifecycle methods, and refs (concepts that we will cover later on), so their use was usually justifiable. Since then, with the introduction ...