diff --git a/content/docs/portals.md b/content/docs/portals.md index 6501213962..f29bb32fab 100644 --- a/content/docs/portals.md +++ b/content/docs/portals.md @@ -4,21 +4,21 @@ title: Portals permalink: docs/portals.html --- -Portals provide a first-class way to render children into a DOM node that exists outside the DOM hierarchy of the parent component. +Portal 提供了一种将子节点渲染到存在于父组件以外的 DOM 节点的优秀的方案。 ```js ReactDOM.createPortal(child, container) ``` -The first argument (`child`) is any [renderable React child](/docs/react-component.html#render), such as an element, string, or fragment. The second argument (`container`) is a DOM element. +第一个参数（`child`）是任何[可渲染的 React 子元素](/docs/react-component.html#render)，例如一个元素，字符串或 fragment。第二个参数（`container`）是一个 DOM 元素。 -## Usage {#usage} +## 用法 {#usage} -Normally, when you return an element from a component's render method, it's mounted into the DOM as a child of the nearest parent node: +通常来讲，当你从组件的 render 方法返回一个元素时，该元素将被挂载到 DOM 节点中离其最近的父节点： ```js{4,6} render() { - // React mounts a new div and renders the children into it + // React 挂载了一个新的 div，并且把子元素渲染其中 return (
{this.props.children} @@ -27,12 +27,12 @@ render() { } ``` -However, sometimes it's useful to insert a child into a different location in the DOM: +然而，有时候将子元素插入到 DOM 节点中的不同位置也是有好处的： ```js{6} render() { - // React does *not* create a new div. It renders the children into `domNode`. - // `domNode` is any valid DOM node, regardless of its location in the DOM. + // React 并*没有*创建一个新的 div。它只是把子元素渲染到 `domNode` 中。 + // `domNode` 是一个可以在任何位置的有效 DOM 节点。 return ReactDOM.createPortal( this.props.children, domNode @@ -40,21 +40,21 @@ render() { } ``` -A typical use case for portals is when a parent component has an `overflow: hidden` or `z-index` style, but you need the child to visually "break out" of its container. For example, dialogs, hovercards, and tooltips. +一个 portal 的典型用例是当父组件有 `overflow: hidden` 或 `z-index` 样式时，但你需要子组件能够在视觉上“跳出”其容器。例如，对话框、悬浮卡以及提示框： -> Note: +> 注意: +> +> 当在使用 portal 时, 记住[管理键盘焦点](/docs/accessibility.html#programmatically-managing-focus)就变得尤为重要。 > -> When working with portals, remember that [managing keyboard focus](/docs/accessibility.html#programmatically-managing-focus) becomes very important. -> -> For modal dialogs, ensure that everyone can interact with them by following the [WAI-ARIA Modal Authoring Practices](https://www.w3.org/TR/wai-aria-practices-1.1/#dialog_modal). +> 对于模态对话框，通过遵循 [WAI-ARIA 模态开发实践](https://www.w3.org/TR/wai-aria-practices-1.1/#dialog_modal)，来确保每个人都能够运用它。 -[**Try it on CodePen**](https://codepen.io/gaearon/pen/yzMaBd) +[**在 CodePen 上尝试**](https://codepen.io/gaearon/pen/yzMaBd) -## Event Bubbling Through Portals {#event-bubbling-through-portals} +## 通过 Portal 进行事件冒泡 {#event-bubbling-through-portals} -Even though a portal can be anywhere in the DOM tree, it behaves like a normal React child in every other way. Features like context work exactly the same regardless of whether the child is a portal, as the portal still exists in the *React tree* regardless of position in the *DOM tree*. +尽管 portal 可以被放置在 DOM 树中的任何地方，但在任何其他方面，其行为和普通的 React 子节点行为一致。由于 portal 仍存在于 *React 树*， 且与 *DOM 树* 中的位置无关，那么无论其子节点是否是 portal，像 context 这样的功能特性都是不变的。 -This includes event bubbling. An event fired from inside a portal will propagate to ancestors in the containing *React tree*, even if those elements are not ancestors in the *DOM tree*. Assuming the following HTML structure: +这包含事件冒泡。一个从 portal 内部触发的事件会一直冒泡至包含 *React 树*的祖先，即便这些元素并不是 *DOM 树* 中的祖先。假设存在如下 HTML 结构： ```html @@ -65,10 +65,10 @@ This includes event bubbling. An event fired from inside a portal will propagate ``` -A `Parent` component in `#app-root` would be able to catch an uncaught, bubbling event from the sibling node `#modal-root`. +在 `#app-root` 里的 `Parent` 组件能够捕获到未被捕获的从兄弟节点 `#modal-root` 冒泡上来的事件。 ```js{28-31,42-49,53,61-63,70-71,74} -// These two containers are siblings in the DOM +// 在 DOM 中有两个容器是兄弟级 （siblings） const appRoot = document.getElementById('app-root'); const modalRoot = document.getElementById('modal-root'); @@ -79,14 +79,14 @@ class Modal extends React.Component { } componentDidMount() { - // The portal element is inserted in the DOM tree after - // the Modal's children are mounted, meaning that children - // will be mounted on a detached DOM node. If a child - // component requires to be attached to the DOM tree - // immediately when mounted, for example to measure a - // DOM node, or uses 'autoFocus' in a descendant, add - // state to Modal and only render the children when Modal - // is inserted in the DOM tree. + // 在 Modal 的所有子元素被挂载后， + // 这个 portal 元素会被嵌入到 DOM 树中， + // 这意味着子元素将被挂载到一个分离的 DOM 节点中。 + // 如果要求子组件在挂载时可以立刻接入 DOM 树， + // 例如衡量一个 DOM 节点， + // 或者在后代节点中使用 ‘autoFocus’， + // 则需添加 state 到 Modal 中， + // 仅当 Modal 被插入 DOM 树中才能渲染子元素。 modalRoot.appendChild(this.el); } @@ -110,9 +110,9 @@ class Parent extends React.Component { } handleClick() { - // This will fire when the button in Child is clicked, - // updating Parent's state, even though button - // is not direct descendant in the DOM. + // 当子元素里的按钮被点击时， + // 这个将会被触发更新父元素的 state， + // 即使这个按钮在 DOM 中不是直接关联的后代 this.setState(state => ({ clicks: state.clicks + 1 })); @@ -137,8 +137,8 @@ class Parent extends React.Component { } function Child() { - // The click event on this button will bubble up to parent, - // because there is no 'onClick' attribute defined + // 这个按钮的点击事件会冒泡到父元素 + // 因为这里没有定义 'onClick' 属性 return (
@@ -149,6 +149,6 @@ function Child() { ReactDOM.render(, appRoot); ``` -[**Try it on CodePen**](https://codepen.io/gaearon/pen/jGBWpE) +[**在 CodePen 上尝试**](https://codepen.io/gaearon/pen/jGBWpE) -Catching an event bubbling up from a portal in a parent component allows the development of more flexible abstractions that are not inherently reliant on portals. For example, if you render a `` component, the parent can capture its events regardless of whether it's implemented using portals. +在父组件里捕获一个来自 portal 冒泡上来的事件，使之能够在开发时具有不完全依赖于 portal 的更为灵活的抽象。例如，如果你在渲染一个 `` 组件，无论其是否采用 portal 实现，父组件都能够捕获其事件。