vant的按需引入組件

強烈建議是按需引入，這樣不占太多空間

步驟：

1.安裝Vant：npm i vant -S

2.安裝babel 插件：npm i babel-plugin-import -D

3.在.babelrc 中添加配置(如果你的項目沒有這個文件，就直接跳到步驟4，忽略此步）

"plugins": [    ["import", {
    "libraryName": "vant",
    "libraryDirectory": "es",
    "style": true
  }],"transform-vue-jsx", "transform-runtime"]

4.在babel.config.js中配置

module.exports = {
  presets: ['@vue/cli-plugin-babel/preset'],
  plugins: [
    [
      'import',
      {
        libraryName: 'vant',
        libraryDirectory: 'es',
        style: true,
      },
      'vant',
    ],
  ],
};

5.在頁面中引入即可

import Vue from "vue";
import { CountDown } from "vant";
Vue.use(CountDown);