Question

导航守卫

全局前置守卫beforeEach

• to: Route， 即将要进入的目标 路由对象；
• from: Route，当前导航正要离开的路由；
• next(): 进行管道中的下一个钩子。如果全部钩子执行完了，则导航的状态就是 confirmed (确认的)。
  • next(false): 中断当前的导航。如果浏览器的 URL 改变了 (可能是用户手动或者浏览器后退按钮)，那么 URL 地址会重置到 from 路由对应的地址。
  • next('/') 或者 next({ path: '/' }): 跳转到一个不同的地址。当前的导航被中断，然后进行一个新的导航。

router.beforeEach((to, form, next) => {
    next()
})

案例:权限判断

const whileList = ['/']

router.beforeEach((to, from, next) => {
    let token = localStorage.getItem('token')
    //白名单 有值 或者登陆过存储了token信息可以跳转 否则就去登录页面
    if (whileList.includes(to.path) || token) {
        next()
    } else {
        next({
            path:'/'
        })
    }
})

全局后置守卫afterEach

使用场景一般可以用来做loadingBar

和守卫不同的是，这些钩子不会接受 next 函数也不会改变导航本身：

router.afterEach((to,from)=>{
    Vnode.component?.exposed?.endLoading()
})

loadingBar 组件

<template>
    <div class="wraps">
        <div ref="bar" class="bar"></div>
    </div>
</template>

<script setup lang='ts'>
import { ref, onMounted } from 'vue'
let speed = ref<number>(1)
let bar = ref<HTMLElement>()
let timer = ref<number>(0)
const startLoading = () => {
    let dom = bar.value as HTMLElement;
    speed.value = 1
    timer.value = window.requestAnimationFrame(function fn() {
        if (speed.value < 90) {
            speed.value += 1;
            dom.style.width = speed.value + '%'
            timer.value = window.requestAnimationFrame(fn)
        } else {
            speed.value = 1;
            window.cancelAnimationFrame(timer.value)
        }
    })

}

const endLoading = () => {
    let dom = bar.value as HTMLElement;
    let timer = setTimeout(() => {
        window.requestAnimationFrame(() => {
            speed.value = 100;
            dom.style.width = speed.value + '%';
        })
          speed.value === 100 && clearTimeout(timer);
    }, 500)
}

defineExpose({
    startLoading,
    endLoading
})
</script>

<style scoped lang="less">
.wraps {
    position: fixed;
    top: 0;
    width: 100%;
    height: 2px;
    .bar {
        height: inherit;
        width: 0;
        background: blue;
    }
}
</style>

mian.ts

import loadingBar from './components/loadingBar.vue'
const Vnode = createVNode(loadingBar)
render(Vnode, document.body)
console.log(Vnode);

router.beforeEach((to, from, next) => {
    Vnode.component?.exposed?.startLoading()
})

router.afterEach((to, from) => {
    Vnode.component?.exposed?.endLoading()
})