vue3如何使用keep alive实现前进更新后退销毁

keep alive实现前进更新后退销毁

想要实现前进更新后退销毁，核心在操作keep-alive的include。
具体做法就是当进入新页面时将页面name保存，再次进入就将它之后的name删除。

具体实现思路：

正常情况下页面是线性前进的：

A->B->C->D

include数组数据[A,B,C,D]

当再次进入C，就认为是D返回C

include数组数据[A,B,C]

D页面就被销毁了,从而实现了后退销毁

使用vuex保存include数组

const keep = {
    namespaced: true,
    state: () => {
        return {
            include: [],
        }
    },
    getters: {
        include(state) {
            return state.include
        },
    },
    mutations: {
        add(state, name) {
            let b = false
            let i = 0
            for (; i < state.include.length; ++i) {
                let e = state.include[i]
                if (e == name) {
                    b = true
                    break
                }
            }
            if (!b) {
                state.include.push(name)
            } else {
                state.include.splice(i + 1)
            }
        }
    },
    actions: {
    }
}
export default keep

在beforeEach中添加name

import store from "../store"
router.beforeEach((to, from,next) => {
// 页面name要和route 的name一样
  store.commit("keep/add", to.name)
  next()
})

include使用

<template>
  <router-view v-slot="{ Component }">
    <keep-alive :include="includeList">
      <component :is="Component" />
    </keep-alive>
  </router-view>
</template>
<script>
export default {
  computed: {
    includeList() {
      return this.$store.getters["keep/include"].join(",");
    },
  },
};
</script>

当然还有页面循环跳转的情况，一般是详情页

A->A->A->A 或A->B->C->A->B->C

这种情况如果不需要保存页面，就用wacth监控$route变化 重新请求接口

如果需要保存页面，就用动态路由addRoute添加新的路由

A1->A2->A3->A4

import time from "../views/time"
function copyObj(obj) {
    if (typeof obj == "object") {
        if (Array.isArray(obj)) {
            let arr = [];
            for (let item of obj) {
                arr.push(Object.assign(copyObj(item)));
            }
            return arr;
        } else if (obj == null) {
            return null;
        } else {
            let obj1 = {};
            for (let index in obj) {
                obj1[index] = copyObj((obj[index]));
            }
            return obj1;
        }
    } else if (typeof obj == "function") {
        return Object.assign(obj);
    } else if (typeof obj == undefined) {
        return undefined;
    } else {
        return obj;
    }
}
window.pushTime = function () {
    let t = new Date().getTime();
    let path = `/time/${t}`;
    // 深复制component
    time = copyObj(time)
    // component name要和route 的name一样
    time.name = path
    this.$router.addRoute({
        path,
        name: path,
        component: time,
    });
    this.$router.push({
        path,
    });
}

vue2用vue-navigation 非常好用

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