React components should be pure, not "idempotent"

Summary

A blogpost in the React docs confuses idempotence with purity. Even though this might seem a small typo, it is one of essential importance in that blogpost.

Page

https://react.dev/blog/2024/02/15/react-labs-what-we-have-been-working-on-february-2024

Details

Idempotence is a property of a function that it returns the same result if you apply the function twice to itself, for example, the absolute value function abs is idempotent, since, abs(abs(x)) = x. In general terms f : X --> X is idempotent iff f ∘ f = f.

This is confused with a pure function. This is a function that, given the same input, returns the same output. It is side-effect free or written in a "functional" style.

Even if this might seem like a minor mistake; it is one of the essential properties that the compiler should check for and to that extent, especially newer developers should not be confused.

Issue にリンクされている React Labs の 2024 年 2 月のブログ記事を開き、React コンポーネントを idempotent と説明している文を見つけてください。周囲にある純粋性の説明を確認し、ページが意図された性質を正確に説明するよう用語を更新して、レンダリングされたドキュメントを確認してください。