element和vant的按需引入

.babelrc文件

{
  "presets": [
    [
      "env",
      {
        "modules": false,
        "targets": {
          "browsers": [
            "> 1%",
            "last 2 versions",
            "not ie <= 8"
          ]
        }
      }
    ],
    "stage-2"
  ],
  "plugins": [
    "transform-vue-jsx",
    "transform-runtime",
    [ // vant 按需引入
      "import",
      {
        "libraryName": "vant",
        "libraryDirectory": "es",
        "style": true
      }
    ],
    [ // element-ui 按需引入
      "component",
      {
        "libraryName": "element-ui",
        "styleLibraryName": "theme-chalk"
      }
    ]
  ]
}