使用react context 实现vue插槽slot功能

2019-11-19 11:10:16

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首先来看下vue的slot的实现

<base-layout>组件，具名插槽name定义以及默认插槽

<div class="container"> <header>  <slot name="header"></slot> </header> <main>  <slot></slot> </main> <footer>  <slot name="footer"></slot> </footer></div><template>

提供内容渲染的组件

<base-layout> <template v-slot:header>  <h1>Here might be a page title</h1> </template> <p>A paragraph for the main content.</p> <p>And another one.</p> <template v-slot:footer>  <p>Here's some contact info</p> </template></base-layout>

最终会渲染出已下架结构

<base-layout> <template v-slot:header>  <h1>Here might be a page title</h1> </template> <p>A paragraph for the main content.</p> <p>And another one.</p> <template v-slot:footer>  <p>Here's some contact info</p> </template></base-layout>

言归正传，怎样使用react的context实现vue的这一功能呢

1 首先确认下layout组件的结构

import React, { Component } from 'react';import SlotProvider from './SlotProvider'import Slot from './Slot'class AppLayout extends Component { static displayName = 'AppLayout' render () {  return (   <div className="container">    <header>     <Slot name="header"></Slot>    </header>    <main>     <Slot></Slot>    </main>    <footer>     <Slot name="footer"></Slot>    </footer>   </div>  ) }}export default SlotProvider(AppLayout)

2 对此结构输出具体内容的组件

import React, { Component } from 'react';import AppLayout from './AppLayout'import AddOn from './AddOn'export default class App extends Component {  render() {    return (      <AppLayout>        <AddOn slot="header">          <h1>这里可能是一个页面标题</h1>        </AddOn>        <AddOn>          <p>主要内容的一个段落。</p>          <p>另一个段落。</p>        </AddOn>        <AddOn slot="footer">          <p>这里有一些联系信息</p>        </AddOn>      </AppLayout>    )  }}

3 其中AddOn类似于上面vue的template，所以下面来实现这个简单的只是用来提供slot标识和children内容的组件AddOn的实现

import React from 'react';import PropTypes from 'prop-types'const AddOn = () => nullAddOn.propTypes = { slot: PropTypes.string }AddOn.defaultTypes = { slot: '$$default' }AddOn.displayName = 'AddOn'export default AddOn

4 Slot组件

import React from 'react';import { SlotContext } from './SlotProvider'import PropTypes from 'prop-types'const Slot = ({ name, children }) => { return (  <SlotContext.Consumer>   {(value) => {    const addOnRenderer = value.requestAddOnRenderer(name)     return (addOnRenderer && addOnRenderer()) || children || null   }}  </SlotContext.Consumer> )}Slot.displayName = 'Slot'Slot.propTypes = { name: PropTypes.string }Slot.defaultProps = { name: '$$default' }export default Slot

5 接下来就是对Slot进行解析的HOC SlotProvider组件了

import React, { Component } from 'react';function getDisplayName(component) {  return component.displayName || component.name || 'component'}export const SlotContext = React.createContext({  requestAddOnRenderer: () => { }})const SlotProviderHoC = (WrappedComponent) => {  return class extends Component {    static displayName = `SlotProvider(${getDisplayName(WrappedComponent)})`    // 用于缓存每个<AddOn />的内容    addOnRenderers = {}    requestAddOnRenderer = (name) => {      if (!this.addOnRenderers[name]) {        return undefined      }      return () => (        this.addOnRenderers[name]      )    }    render() {      const {        children,        ...restProps      } = this.props      if (children) {        // 以k-v的方式缓存<AddOn />的内容        const arr = React.Children.toArray(children)        const nameChecked = []        this.addOnRenderers = {}        arr.forEach(item => {          const itemType = item.type          console.log('itemType',itemType)          if (item.type.displayName === 'AddOn') {            const slotName = item.props.slot || '$$default'            // 确保内容唯一性            if (nameChecked.findIndex(item => item === slotName) !== -1) {              throw new Error(`Slot(${slotName}) has been occupied`)            }            this.addOnRenderers[slotName] = item.props.children            nameChecked.push(slotName)          }        })      }      return (        <SlotContext.Provider value={{ requestAddOnRenderer: this.requestAddOnRenderer }}>          <WrappedComponent {...restProps} />        </SlotContext.Provider >      )    }  } } export default SlotProviderHoC

6 最终渲染结果