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docs(cn): translate legacy/createElement into Chinese
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RexSkz committed Jun 25, 2023
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102 changes: 51 additions & 51 deletions src/content/reference/react/createElement.md
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Expand Up @@ -4,7 +4,7 @@ title: createElement

<Intro>

`createElement` lets you create a React element. It serves as an alternative to writing [JSX.](/learn/writing-markup-with-jsx)
`createElement` 允许你创建一个 React 元素。它可以作为 [JSX](/learn/writing-markup-with-jsx) 的替代方案。

```js
const element = createElement(type, props, ...children)
Expand All @@ -16,11 +16,11 @@ const element = createElement(type, props, ...children)

---

## Reference {/*reference*/}
## 参考 {/*reference*/}

### `createElement(type, props, ...children)` {/*createelement*/}

Call `createElement` to create a React element with the given `type`, `props`, and `children`.
调用 `createElement` 来创建一个 React 元素,它有 `type``props` `children` 三个参数。

```js
import { createElement } from 'react';
Expand All @@ -29,93 +29,93 @@ function Greeting({ name }) {
return createElement(
'h1',
{ className: 'greeting' },
'Hello'
'你好'
);
}
```

[See more examples below.](#usage)
[查看更多例子](#usage)

#### Parameters {/*parameters*/}
#### 参数 {/*parameters*/}

* `type`: The `type` argument must be a valid React component type. For example, it could be a tag name string (such as `'div'` or `'span'`), or a React component (a function, a class, or a special component like [`Fragment`](/reference/react/Fragment)).
* `type``type` 参数必须是一个有效的 React 组件类型,例如一个字符串标签名(如 `'div'` `'span'`),或一个 React 组件(一个函数式组件、一个类式组件,或者是一个特殊的组件如 [`Fragment`](/reference/react/Fragment))。

* `props`: The `props` argument must either be an object or `null`. If you pass `null`, it will be treated the same as an empty object. React will create an element with props matching the `props` you have passed. Note that `ref` and `key` from your `props` object are special and will *not* be available as `element.props.ref` and `element.props.key` on the returned `element`. They will be available as `element.ref` and `element.key`.
* `props``props` 参数必须是一个对象或 `null`。如果你传入 `null`,它会被当作一个空对象。创建的 React 元素的 `props` 与这个参数相同。注意,`props` 对象中的 `ref` `key` 比较特殊,它们 **不会** 作为 `element.props.ref` `element.props.key` 出现在创建的元素 `element` 上,而是作为 `element.ref` `element.key` 出现。

* **optional** `...children`: Zero or more child nodes. They can be any React nodes, including React elements, strings, numbers, [portals](/reference/react-dom/createPortal), empty nodes (`null`, `undefined`, `true`, and `false`), and arrays of React nodes.
* **可选** `...children`:零个或多个子节点。它们可以是任何 React 节点,包括 React 元素、字符串、数字、[portal](/reference/react-dom/createPortal)、空节点(`null``undefined``true` `false`),以及 React 节点数组。

#### Returns {/*returns*/}
#### 返回值 {/*returns*/}

`createElement` returns a React element object with a few properties:
`createElement` 返回一个 React 元素,它有这些属性:

* `type`: The `type` you have passed.
* `props`: The `props` you have passed except for `ref` and `key`. If the `type` is a component with legacy `type.defaultProps`, then any missing or undefined `props` will get the values from `type.defaultProps`.
* `ref`: The `ref` you have passed. If missing, `null`.
* `key`: The `key` you have passed, coerced to a string. If missing, `null`.
* `type`:你传入的 `type`
* `props`:你传入的 `props`,不包括 `ref` `key`。如果 `type` 是一个组件,且带有过时的 `type.defaultProps` 属性,那么 `props` 中任何缺失或未定义的字段都会采用 `type.defaultProps` 中的值。
* `ref`:你传入的 `ref`。如果缺失则为 `null`
* `key`:你传入的 `key`,会被强制转换为字符串。如果缺失则为 `null`

Usually, you'll return the element from your component or make it a child of another element. Although you may read the element's properties, it's best to treat every element as opaque after it's created, and only render it.
通常你会在你组件的最后返回这个元素,或者把它作为另一个元素的子元素。虽然你可以读取元素的属性,但你最好把创建的元素作为黑盒,只用于渲染。

#### Caveats {/*caveats*/}
#### 注意事项 {/*caveats*/}

* You must **treat React elements and their props as [immutable](https://en.wikipedia.org/wiki/Immutable_object)** and never change their contents after creation. In development, React will [freeze](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/freeze) the returned element and its `props` property shallowly to enforce this.
* 你必须 ** React 元素和它们的 props 视为 [不可变的](https://en.wikipedia.org/wiki/Immutable_object)**,在创建后永远不要改变它们的内容。在开发环境中,React 会浅层 [冻结](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/freeze) 返回的元素及其 `props` 属性,以确保如此。

* When you use JSX, **you must start a tag with a capital letter to render your own custom component.** In other words, `<Something />` is equivalent to `createElement(Something)`, but `<something />` (lowercase) is equivalent to `createElement('something')` (note it's a string, so it will be treated as a built-in HTML tag).
* 当你使用 JSX 时,**你必须以大写字母开头来渲染你的自定义组件**。换句话说,`<Something />` 等价于 `createElement(Something)`,但 `<something />`(小写)等价于 `createElement('something')`(注意它是一个字符串,它会被当作内置的 HTML 标签)。

* You should only **pass children as multiple arguments to `createElement` if they are all statically known,** like `createElement('h1', {}, child1, child2, child3)`. If your children are dynamic, pass the entire array as the third argument: `createElement('ul', {}, listItems)`. This ensures that React will [warn you about missing `key`s](/learn/rendering-lists#keeping-list-items-in-order-with-key) for any dynamic lists. For static lists this is not necessary because they never reorder.
* 你应该仅 **在所有子元素都是静态可知的情况下,才将它们依次传递给 `createElement` 的可选参数**,比如 `createElement('h1', {}, child1, child2, child3)`。如果你的子元素不固定,则把它们放到数组中作为第三个参数传递,例如 `createElement('ul', {}, listItems)`,以此确保 React 可以在动态列表的场景下 [警告你缺少 `key`](/learn/rendering-lists#keeping-list-items-in-order-with-key)。静态列表的场景不需要这么做,因为它们不会重新排序。

---

## Usage {/*usage*/}
## 用法 {/*usage*/}

### Creating an element without JSX {/*creating-an-element-without-jsx*/}
## 不使用 JSX 创建元素 {/*creating-an-element-without-jsx*/}

If you don't like [JSX](/learn/writing-markup-with-jsx) or can't use it in your project, you can use `createElement` as an alternative.
如果你不喜欢 [JSX](/learn/writing-markup-with-jsx) 或者无法在你的项目中使用它,你可以使用 `createElement` 作为替代方案。

To create an element without JSX, call `createElement` with some <CodeStep step={1}>type</CodeStep>, <CodeStep step={2}>props</CodeStep>, and <CodeStep step={3}>children</CodeStep>:
要想不使用 JSX 创建一个元素,你可以调用 `createElement` 并传入 <CodeStep step={1}>type</CodeStep><CodeStep step={2}>props</CodeStep> <CodeStep step={3}>children</CodeStep>

```js [[1, 5, "'h1'"], [2, 6, "{ className: 'greeting' }"], [3, 7, "'Hello ',"], [3, 8, "createElement('i', null, name),"], [3, 9, "'. Welcome!'"]]
```js [[1, 5, "'h1'"], [2, 6, "{ className: 'greeting' }"], [3, 7, "'你好',"], [3, 8, "createElement('i', null, name),"], [3, 9, "'。欢迎!'"]]
import { createElement } from 'react';

function Greeting({ name }) {
return createElement(
'h1',
{ className: 'greeting' },
'Hello ',
'你好',
createElement('i', null, name),
'. Welcome!'
'。欢迎!'
);
}
```

The <CodeStep step={3}>children</CodeStep> are optional, and you can pass as many as you need (the example above has three children). This code will display a `<h1>` header with a greeting. For comparison, here is the same example rewritten with JSX:
<CodeStep step={3}>children</CodeStep> 是可选的,你可以传入任意数量的子元素(上面的例子中有三个)。这段代码会显示一个带有问候语的 `<h1>` 标题。为了对比,这是使用 JSX 的版本:

```js [[1, 3, "h1"], [2, 3, "className=\\"greeting\\""], [3, 4, "Hello <i>{name}</i>. Welcome!"], [1, 5, "h1"]]
```js [[1, 3, "h1"], [2, 3, "className=\\"greeting\\""], [3, 4, "你好<i>{name}</i>,欢迎!"], [1, 5, "h1"]]
function Greeting({ name }) {
return (
<h1 className="greeting">
Hello <i>{name}</i>. Welcome!
你好<i>{name}</i>,欢迎!
</h1>
);
}
```

To render your own React component, pass a function like `Greeting` as the <CodeStep step={1}>type</CodeStep> instead of a string like `'h1'`:
要想渲染你自己的 React 组件,则传入一个函数(比如 `Greeting`)作为 <CodeStep step={1}>type</CodeStep> ,而不是一个字符串(比如 `'h1'`):

```js [[1, 2, "Greeting"], [2, 2, "{ name: 'Taylor' }"]]
```js [[1, 2, "Greeting"], [2, 2, "{ name: '泰勒' }"]]
export default function App() {
return createElement(Greeting, { name: 'Taylor' });
return createElement(Greeting, { name: '泰勒' });
}
```

With JSX, it would look like this:
如果使用 JSX,它看起来像这样:

```js [[1, 2, "Greeting"], [2, 2, "name=\\"Taylor\\""]]
```js [[1, 2, "Greeting"], [2, 2, "name=\\"泰勒\\""]]
export default function App() {
return <Greeting name="Taylor" />;
return <Greeting name="泰勒" />;
}
```

Here is a complete example written with `createElement`:
这里是一个完整的使用 `createElement` 的示例:

<Sandpack>

Expand All @@ -126,16 +126,16 @@ function Greeting({ name }) {
return createElement(
'h1',
{ className: 'greeting' },
'Hello ',
'你好',
createElement('i', null, name),
'. Welcome!'
',欢迎!'
);
}

export default function App() {
return createElement(
Greeting,
{ name: 'Taylor' }
{ name: '泰勒' }
);
}
```
Expand All @@ -149,21 +149,21 @@ export default function App() {

</Sandpack>

And here is the same example written using JSX:
这里是相同的示例,但使用的是 JSX

<Sandpack>

```js
function Greeting({ name }) {
return (
<h1 className="greeting">
Hello <i>{name}</i>. Welcome!
你好<i>{name}</i>,欢迎!
</h1>
);
}

export default function App() {
return <Greeting name="Taylor" />;
return <Greeting name="泰勒" />;
}
```

Expand All @@ -176,30 +176,30 @@ export default function App() {

</Sandpack>

Both coding styles are fine, so you can use whichever one you prefer for your project. The main benefit of using JSX compared to `createElement` is that it's easy to see which closing tag corresponds to which opening tag.
两种编码风格都没问题,你可以在项目中使用任何一个你喜欢的风格。相比于 `createElement`,使用 JSX 的主要好处是很容易看出哪个闭合标签对应哪个开放标签。

<DeepDive>

#### What is a React element, exactly? {/*what-is-a-react-element-exactly*/}
#### React 元素究竟是什么? {/*what-is-a-react-element-exactly*/}

An element is a lightweight description of a piece of the user interface. For example, both `<Greeting name="Taylor" />` and `createElement(Greeting, { name: 'Taylor' })` produce an object like this:
元素是用来描述一部分用户界面的轻量级结构。比如,`<Greeting name="泰勒" />` `createElement(Greeting, { name: '泰勒' })` 都会生成一个这样的对象:

```js
// Slightly simplified
// 极度简化的样子
{
type: Greeting,
props: {
name: 'Taylor'
name: '泰勒'
},
key: null,
ref: null,
}
```

**Note that creating this object does not render the `Greeting` component or create any DOM elements.**
**注意,创建这个对象并不会渲染 `Greeting` 组件或者创建任何 DOM 元素**

A React element is more like a description--an instruction for React to later render the `Greeting` component. By returning this object from your `App` component, you tell React what to do next.
React 元素更像是一个描述或指令,它告诉 React 之后该如何渲染 `Greeting` 组件。你从 `App` 组件中返回了这个对象,就是告诉了 React 接下来该做什么。

Creating elements is extremely cheap so you don't need to try to optimize or avoid it.
创建元素非常高效,因此你不需要试图优化或者避免它。

</DeepDive>

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