diff --git a/src/content/reference/react/PureComponent.md b/src/content/reference/react/PureComponent.md index 3e2d074e10..ed6ff75b7d 100644 --- a/src/content/reference/react/PureComponent.md +++ b/src/content/reference/react/PureComponent.md @@ -4,13 +4,13 @@ title: PureComponent -We recommend defining components as functions instead of classes. [See how to migrate.](#alternatives) +我们建议使用函数式组件而非类式组件。[查看如何迁移](#alternatives)。 -`PureComponent` is similar to [`Component`](/reference/react/Component) but it skips re-renders for same props and state. Class components are still supported by React, but we don't recommend using them in new code. +`PureComponent` 类似于 [`Component`](/reference/react/Component),但是当 props 和 state 与之前保持一致时会跳过重新渲染。React 仍然支持类式组件,但我们不建议在新代码中使用。 ```js class Greeting extends PureComponent { @@ -26,11 +26,11 @@ class Greeting extends PureComponent { --- -## Reference {/*reference*/} +## 参考 {/*reference*/} ### `PureComponent` {/*purecomponent*/} -To skip re-rendering a class component for same props and state, extend `PureComponent` instead of [`Component`:](/reference/react/Component) +为了在 props 和 state 相同时跳过重新渲染,类式组件应该继承 `PureComponent` 而不是 [`Component`](/reference/react/Component): ```js import { PureComponent } from 'react'; @@ -42,18 +42,18 @@ class Greeting extends PureComponent { } ``` -`PureComponent` is a subclass of `Component` and supports [all the `Component` APIs.](/reference/react/Component#reference) Extending `PureComponent` is equivalent to defining a custom [`shouldComponentUpdate`](/reference/react/Component#shouldcomponentupdate) method that shallowly compares props and state. +`PureComponent` 是 `Component` 的子类,并且支持 [所有 `Component` 的 API](/reference/react/Component#reference)。继承 `PureComponent` 的子类相当与定义了一个自定义的 [`shouldComponentUpdate`](/reference/react/Component#shouldcomponentupdate) 方法,该方法将浅比较 props 和 state。 -[See more examples below.](#usage) +[请参阅以下更多示例](#usage)。 --- -## Usage {/*usage*/} +## 用法 {/*usage*/} -### Skipping unnecessary re-renders for class components {/*skipping-unnecessary-re-renders-for-class-components*/} +### 跳过类式组件不必要的重新渲染 {/*skipping-unnecessary-re-renders-for-class-components*/} -React normally re-renders a component whenever its parent re-renders. As an optimization, you can create a component that React will not re-render when its parent re-renders so long as its new props and state are the same as the old props and state. [Class components](/reference/react/Component) can opt into this behavior by extending `PureComponent`: +当父组件重新渲染时,React 通常会重新渲染子组件。为了优化性能,你可以创建一个组件,在父组件重新渲染时不会重新渲染,前提是新的 props 和 state 与旧的 props 和 state 相同。[类式组件](/reference/react/Component) 可以通过继承 `PureComponent` 来选择此行为。 ```js {1} class Greeting extends PureComponent { @@ -63,9 +63,9 @@ class Greeting extends PureComponent { } ``` -A React component should always have [pure rendering logic.](/learn/keeping-components-pure) This means that it must return the same output if its props, state, and context haven't changed. By using `PureComponent`, you are telling React that your component complies with this requirement, so React doesn't need to re-render as long as its props and state haven't changed. However, your component will still re-render if a context that it's using changes. +React 组件应该始终具有 [纯粹的渲染逻辑](/learn/keeping-components-pure)。这意味着如果 props、state 和 context 没有发生变化,它必须返回相同的输出。使用 `PureComponent` 便是在告诉 React 你的组件符合这个要求,因此只要 props 和 state 没有改变,React 就不需要重新渲染组件。然而,如果你的组件正在使用的 context 发生变化,它仍会重新渲染。 -In this example, notice that the `Greeting` component re-renders whenever `name` is changed (because that's one of its props), but not when `address` is changed (because it's not passed to `Greeting` as a prop): +注意,在这个例子中,`Greeting` 组件会在 `name` 改变时重新渲染(因为这是它的 props),但在 `address` 改变时不会(因为它没有作为 props 传递给 `Greeting`): @@ -109,17 +109,17 @@ label { -We recommend defining components as functions instead of classes. [See how to migrate.](#alternatives) +我们建议使用函数式组件而非类式组件。[查看如何迁移](#alternatives)。 --- -## Alternatives {/*alternatives*/} +## 替代方案 {/*alternatives*/} -### Migrating from a `PureComponent` class component to a function {/*migrating-from-a-purecomponent-class-component-to-a-function*/} +### 从 `PureComponent` 类式组件迁移到函数式组件 {/*migrating-from-a-purecomponent-class-component-to-a-function*/} -We recommend using function components instead of [class components](/reference/react/Component) in new code. If you have some existing class components using `PureComponent`, here is how you can convert them. This is the original code: +我们建议在新代码中使用函数式组件,而不是 [类式组件](/reference/react/Component)。如果你有一些使用 `PureComponent` 的现有组件,以下是如何进行转换。这是原始代码: @@ -161,7 +161,7 @@ label { -When you [convert this component from a class to a function,](/reference/react/Component#alternatives) wrap it in [`memo`:](/reference/react/memo) +当你 [将这个组件从类式组件转换为函数式组件](/reference/react/Component#alternatives) 时,将其包装在 [`memo`](/reference/react/memo): @@ -203,6 +203,6 @@ label { -Unlike `PureComponent`, [`memo`](/reference/react/memo) does not compare the new and the old state. In function components, calling the [`set` function](/reference/react/useState#setstate) with the same state [already prevents re-renders by default,](/reference/react/memo#updating-a-memoized-component-using-state) even without `memo`. +与 `PureComponent` 不同,[`memo`](/reference/react/memo) 不会比较新旧 state。在函数组件中,即使没有 `memo`,调用具有相同 state 的 [`set` 函数](/reference/react/useState#setstate),[默认已经阻止了重新渲染](/reference/react/memo#updating-a-memoized-component-using-state)。