React中实现keepalive组件缓存效果(react keepalive)

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React中实现keepalive组件缓存效果

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背景：由于react官方并没有提供缓存组件相关的api（类似vue中的keepalive），在某些场景，会使得页面交互性变的很差，比如在有搜索条件的表格页面，点击某一条数据跳转到详情页面，再返回表格页面，会重新请求数据，搜索条件也将清空，用户得重新输入搜索条件，再次请求数据，大大降低办公效率，如图：

目标：封装keepalive缓存组件，实现组件的缓存，并暴露相关方法，可以手动清除缓存。

React中实现keepalive组件缓存效果(react keepalive)

版本：React 17，react-router-dom 5

结构：

代码：

cache-types.js

// 缓存状态export const CREATE = 'CREATE'; // 创建export const CREATED = 'CREATED'; // 创建成功export const ACTIVE = 'ACTIVE'; // 激活export const DESTROY = 'DESTROY'; // 销毁

CacheContext.js

import React from 'react';const CacheContext = React.createContext();export default CacheContext;

cacheReducer.js

import * as cacheTypes from "./cache-types";function cacheReducer(cacheStates = {}, { type, payload }) { switch (type) { case cacheTypes.CREATE: return { ...cacheStates, [payload.cacheId]: { scrolls: {}, // 缓存滚动条，key: dom, value: scrollTop cacheId: payload.cacheId, // 缓存Id element: payload.element, // 需要渲染的虚拟DOM doms: undefined, // 当前的虚拟dom所对应的真实dom status: cacheTypes.CREATE,// 缓存状态 }, }; case cacheTypes.CREATED: return { ...cacheStates, [payload.cacheId]: { ...cacheStates[payload.cacheId], doms: payload.doms, status: cacheTypes.CREATED, }, }; case cacheTypes.ACTIVE: return { ...cacheStates, [payload.cacheId]: { ...cacheStates[payload.cacheId], status: cacheTypes.ACTIVE, }, }; case cacheTypes.DESTROY: return { ...cacheStates, [payload.cacheId]: { ...cacheStates[payload.cacheId], status: cacheTypes.DESTROY, }, }; default: return cacheStates; }}export default cacheReducer;

KeepAliveProvider.js

import React, { useReducer, useCallback } from "react";import CacheContext from "./CacheContext";import cacheReducer from "./cacheReducer";import * as cacheTypes from "./cache-types";function KeepAliveProvider(props) { let [cacheStates, dispatch] = useReducer(cacheReducer, {}); const mount = useCallback( ({ cacheId, element }) => { // 挂载元素方法，提供子组件调用挂载元素 if (cacheStates[cacheId]) { let cacheState = cacheStates[cacheId]; if (cacheState.status === cacheTypes.DESTROY) { let doms = cacheState.doms; doms.forEach((dom) => dom.parentNode.removeChild(dom)); dispatch({ type: cacheTypes.CREATE, payload: { cacheId, element } }); // 创建缓存 } } else { dispatch({ type: cacheTypes.CREATE, payload: { cacheId, element } }); // 创建缓存 } }, [cacheStates] ); let handleScroll = useCallback( // 缓存滚动条 (cacheId, { target }) => { if (cacheStates[cacheId]) { let scrolls = cacheStates[cacheId].scrolls; scrolls[target] = target.scrollTop; } }, [cacheStates] ); return ( <CacheContext.Provider value={{ mount, cacheStates, dispatch, handleScroll }} > {props.children} {/* cacheStates维护所有缓存信息， dispatch派发修改缓存状态*/} {Object.values(cacheStates) .filter((cacheState) => cacheState.status !== cacheTypes.DESTROY) .map(({ cacheId, element }) => ( <div id={`cache_${cacheId}`} key={cacheId} // 原生div中

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