vue 按需引入vant跟全局引入方式

npm i vant -S

npm i vant@next -S

  "dependencies": {
    "axios": "^0.21.1",
    "core-js": "^2.6.5",
    "fastclick": "^1.0.6",
    "vant": "^2.12.20",
    "vue": "^2.6.10",
    "vue-router": "^3.0.3",
    "vuex": "^3.0.1"
  },

npm i babel-plugin-import -D

// 在.babelrc 中添加配置
// 注意：webpack 1 无需设置 libraryDirectory

{
    "plugins": [
      ["import", {
        "libraryName": "vant",
        "libraryDirectory": "es",
        "style": true
      }]
    ]
  }

import Vue from 'vue'
import { Button } from 'vant';
import { ImagePreview } from 'vant';
import { Image as VanImage } from 'vant';
import { Swipe, SwipeItem } from 'vant';
import { Grid, GridItem } from 'vant';
import { Card } from 'vant';
import { Tag } from 'vant';
import { Icon } from 'vant';
Vue.use(Icon);
Vue.use(Tag);
Vue.use(Card);
Vue.use(Grid);
Vue.use(GridItem);
Vue.use(Swipe);
Vue.use(SwipeItem);
Vue.use(VanImage);
// 全局注册
Vue.use(ImagePreview);
Vue.use(Button)

import './vant/vant'

<van-button type="info">信息按钮</van-button>
<van-button type="default">默认按钮</van-button>
<van-button type="warning">警告按钮</van-button>
<van-button type="danger">危险按钮</van-button>

import Vant from 'vant';
import 'vant/lib/index.css';
Vue.use(Vant);

<van-button type="info">信息按钮</van-button>
<van-button type="default">默认按钮</van-button>
<van-button type="warning">警告按钮</van-button>
<van-button type="danger">危险按钮</van-button>