本文主要介绍了react-router-dom v6 通过outlet实现keepAlive 功能的实现，具体如下：
keepAlive代码：
import React, { useRef, useEffect, useReducer, useMemo, memo } from 'react'
import { TransitionGroup, CSSTransition } from 'react-transition-group'
import { useLocation } from 'react-router-dom'
const KeepAlive = props => {
const { include, keys, children } = props
const { pathname } = useLocation()
const componentList = useRef(new Map())
const forceUpdate = useReducer(bool => !bool)[1] // 强制渲染
const cacheKey = useMemo(() => pathname + "__" + keys[pathname], [pathname, keys]) // eslint-disable-line
const activeKey = useRef(null)
useEffect(() => {
componentList.current.forEach(function(value, key) {
const _key = key.split("__")[0]
if (!include.includes(_key) || (_key === pathname)) {
this.delete(key)
}
}, componentList.current)
activeKey.current = cacheKey
if (!componentList.current.has(activeKey.current)) {
componentList.current.set(activeKey.current, children)
}
forceUpdate()
}, [cacheKey, include]) // eslint-disable-line
return (
<TransitionGroup component={ null }>
{
Array.from(componentList.current).map(([key, component]) =>
<CSSTransition
key={ key }
appear={ true }
timeout={ 500 }
classNames='fade'>
{
key === activeKey.current ?
<div
className={
`layout-container${include.includes(key.split("__")[0]) ? " keep-alive-fade": ""}`
}>
{ component }
</div> :
<div
className='layout-container__keep-alive'
style={{ display: 'none' }}>
{ component }
</div>
}
</CSSTransition>
)
}
</TransitionGroup>
)
}
export default memo(KeepAlive)
main.js 中调用
import PropTypes from 'prop-types'
import { useLocation, useOutlet } from 'react-router-dom'
import { connect } from 'react-redux'
import { Layout } from 'antd'
import { TransitionGroup, CSSTransition } from 'react-transition-group'
import KeepAlive from '@/components/common/keepAlive'
import { isKeepAlive } from '@/service/config'
const Main = props => {
const { fullScreen, cacheRoutes, cacheKeys } = props
const outlet = useOutlet()
const { pathname } = useLocation()
return (
<Layout.Content className={{ "layout-main": true, "full-screen": fullScreen }}>
<section>
{
// isKeepAlive 生产环境中启用缓存
isKeepAlive ?
<KeepAlive include={ cacheRoutes } keys={ cacheKeys }>
{ outlet } // 此处不能用 <Outlet /> 不然无法通过 useRef 来缓存
</KeepAlive> :
<TransitionGroup component={ null }>
<CSSTransition
key={ pathname + cacheKeys[pathname] }
appear={ true }
timeout={ 500 }
classNames='page-fade'>
{ outlet } // 此处不能用 <Outlet /> 会造成路由切换时，组件重复渲染
</CSSTransition>
</TransitionGroup>
}
</section>
</Layout.Content>
)
}
Main.propTypes = {
fullScreen: PropTypes.bool,
cacheRoutes: PropTypes.array,
cacheKeys: PropTypes.object
}
const mapStateToProps = state => {
return {
fullScreen: state.setting.fullScreen,
cacheRoutes: state.tabsBar.cacheRoutes, // 需要缓存的路由组件path数组
cacheKeys: state.tabsBar.cacheKeys // 用于组件局部刷新
}
}
export default connect(mapStateToProps)(Main)
1、当前图片动画中，只设置了第二个标签页缓存，其他的几个未开启缓存，所以可以看到，只有第二个标签页在切回的时候 未重新请求数据。其他标签页每次进入都会重新请求数据。
2、此外这里结合react-transition-group 实现了路由切换的渐隐渐显动画，但需要手动配合css样式控制，不能完全依靠CSSTransition
代码部分：
// 路由进入动画
.fade-enter, .fade-appear {
opacity: 0;
}
.fade-enter-active, .fade-appear-active {
opacity: 1;
@include transition(opacity .25s cubic-bezier(.645, .045, .355, 1) .25s);
}
.fade-exit {
opacity: 1;
z-index: 1;
}
.fade-exit-active {
opacity: 0;
z-index: 1;
@include transition(opacity .25s cubic-bezier(.645, .045, .355, 1));
}
.page-fade-enter, .page-fade-appear {
opacity: 0;
}
.page-fade-enter-active, .page-fade-appear-active {
opacity: 1;
@include transition(opacity .5s cubic-bezier(.645, .045, .355, 1));
}
.page-fade-exit {
opacity: 1;
display: none!important;
}
.page-fade-exit-active {
opacity: 0;
}
@keyframes keepAliveFade {
0% { opacity: 0; }
50% { opacity: 0; }
100% { opacity: 1; }
}
.layout-container {
position: absolute;
left: 0;
right: 0;
top: 0;
bottom: 0;
&.keep-alive-fade { animation: keepAliveFade .5s ease-in-out; }
}
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