npm i -S vant

// .babelrc or babel-loader option
{
  "plugins": [
    ["import", { "libraryName": "vant", "style": true }]
  ]
}

  // 模块化地引入 js 和 css, 通过 babel-plugin-import 插件解析
  import { Button } from 'vant';

import { Button } from 'vant/lib/button';
import 'vant/lib/vant-css/button.css';

import Vue from 'vue';
import vant from 'vant';
import 'vant/lib/vant-css/index.css';

Vue.use(vant);

make init componentName

npm run dev