Failed to resolve import “element-plus/es/components/submenu/style/css“ from “src/components/trimxxx

这是在 vue2 升级 vue3 项目的时候遇到的，先说一下原因

在 element-ui中，使用submenu是这样的，官网截图：

在element-plus中，使用submenu是这样的，官网截图：

下面来说一下解决思路

这是vue2的代码：

<template>
  <div>
    <el-menu
      default-active="2"
      class="el-menu-vertical-demo"
      @open="handleOpen"
      @close="handleClose"
    >
      <el-submenu index="1">
        <template slot="title">
          <i class="el-icon-location"></i>
          <span>导航一</span>
        </template>
        <el-menu-item-group>
          <template slot="title">分组一</template>
          <el-menu-item index="1-1">选项1</el-menu-item>
          <el-menu-item index="1-2">选项2</el-menu-item>
        </el-menu-item-group>
        <el-menu-item-group title="分组2">
          <el-menu-item index="1-3">选项3</el-menu-item>
        </el-menu-item-group>
        <el-submenu index="1-4">
          <template slot="title">选项4</template>
          <el-menu-item index="1-4-1">选项1</el-menu-item>
        </el-submenu>
      </el-submenu>
      <el-menu-item index="2">
        <i class="el-icon-menu"></i>
        <span slot="title">导航二</span>
      </el-menu-item>
      <el-menu-item index="3" disabled>
        <i class="el-icon-document"></i>
        <span slot="title">导航三</span>
      </el-menu-item>
      <el-menu-item index="4">
        <i class="el-icon-setting"></i>
        <span slot="title">导航四</span>
      </el-menu-item>
    </el-menu>
  </div>
</template>

<script>
export default {
  name: 'test',
  methods: {
    handleOpen(key, keyPath) {
      console.log(key, keyPath)
    },
    handleClose(key, keyPath) {
      console.log(key, keyPath)
    },
  },
}
</script>

<style lang="" scoped></style>

这是升级到vue3之后的代码：

<script setup lang="ts">
const handleOpen = (key: any, keyPath: any) => {
  console.log(key, keyPath)
}
const handleClose = (key: any, keyPath: any) => {
  console.log(key, keyPath)
}
</script>
<template>
  <div>
    <el-menu
      default-active="2"
      class="el-menu-vertical-demo"
      @open="handleOpen"
      @close="handleClose"
    >
      <el-submenu index="1">
        <template slot="title">
          <i class="el-icon-location"></i>
          <span>导航一</span>
        </template>
        <el-menu-item-group>
          <template slot="title">分组一</template>
          <el-menu-item index="1-1">选项1</el-menu-item>
          <el-menu-item index="1-2">选项2</el-menu-item>
        </el-menu-item-group>
        <el-menu-item-group title="分组2">
          <el-menu-item index="1-3">选项3</el-menu-item>
        </el-menu-item-group>
        <el-submenu index="1-4">
          <template slot="title">选项4</template>
          <el-menu-item index="1-4-1">选项1</el-menu-item>
        </el-submenu>
      </el-submenu>
      <el-menu-item index="2">
        <i class="el-icon-menu"></i>
        <span slot="title">导航二</span>
      </el-menu-item>
      <el-menu-item index="3" disabled>
        <i class="el-icon-document"></i>
        <span slot="title">导航三</span>
      </el-menu-item>
      <el-menu-item index="4">
        <i class="el-icon-setting"></i>
        <span slot="title">导航四</span>
      </el-menu-item>
    </el-menu>
  </div>
</template>

<style lang="less" scoped></style>

报错是[vite] Internal server error: Failed to resolve import "element-plus/es/components/submenu/style/css" from "src/components/trimxxx.vue". Does the file exist?，我们看自动引入element-plus的文件：

找到这个东西，是引入的，那么我们就去官网找 element-ui 和 element-plus 的使用案例对比一下，看看差别就好了