理解按需自动导入 unplugin-auto-import & unplugin-vue-components

发布时间:2023年12月21日

在这里插入图片描述

unplugin-auto-import

Auto import APIs on-demand for Vite, Webpack, Rspack, Rollup and esbuild. With TypeScript support. Powered by unplugin.

基础使用

项目中的 js 模块可以使用 unplugin-auto-import 来自动引入。

比如 vue 的一些 api,ref,reactive 等,可以不用手动导入。但要明白插件只是帮助我们在编译时自动添加 import,而不是代码中可以没有 import 导入。

看看 element-plus 的自动引入配置:

import AutoImport from "unplugin-auto-import/vite";
import Components from "unplugin-vue-components/vite";
import { ElementPlusResolver } from "unplugin-vue-components/resolvers";

export default defineConfig(({ command }) => {
    return {
        plugins: [
            vue(),
            AutoImport({
                resolvers: [ElementPlusResolver({ importStyle: "sass" })],
                eslintrc: {
                    enabled: true
                }
            }),
            Components({
                resolvers: [ElementPlusResolver({ importStyle: "sass" })]
            })
          ]
    }
}

安装:

pnpm i -D unplugin-auto-import

构建工具引入插件

因为上面是 vite 中使用,因此引入 unplugin-vue-components 的 vite 插件版本unplugin-vue-components/vite

其他常见构建工具引入:webpack、vue cli

// webpack.config.js & vue.config.js
module.exports = {
  /* ... */
  plugins: [
    require('unplugin-auto-import/webpack').default({ /* options */ }),
  ],
}

配置插件

AutoImport({
  // targets to transform
  include: [
    /\.[tj]sx?$/, // .ts, .tsx, .js, .jsx
    /\.vue$/,
    /\.vue\?vue/, // .vue
    /\.md$/, // .md
  ],

  // global imports to register
  imports: [
    // presets
    'vue',
    'vue-router',
    // custom
    {
      '@vueuse/core': [
        // named imports
        'useMouse', // import { useMouse } from '@vueuse/core',
        // alias
        ['useFetch', 'useMyFetch'], // import { useFetch as useMyFetch } from '@vueuse/core',
      ],
      'axios': [
        // default imports
        ['default', 'axios'], // import { default as axios } from 'axios',
      ],
      '[package-name]': [
        '[import-names]',
        // alias
        ['[from]', '[alias]'],
      ],
    },
    // example type import
    {
      from: 'vue-router',
      imports: ['RouteLocationRaw'],
      type: true,
    },
  ],
  // Enable auto import by filename for default module exports under directories
  defaultExportByFilename: false,

  // Auto import for module exports under directories
  // by default it only scan one level of modules under the directory
  dirs: [
    // './hooks',
    // './composables' // only root modules
    // './composables/**', // all nested modules
    // ...
  ],

  // Filepath to generate corresponding .d.ts file.
  // Defaults to './auto-imports.d.ts' when `typescript` is installed locally.
  // Set `false` to disable.
  dts: './auto-imports.d.ts',

  // Auto import inside Vue template
  // see https://github.com/unjs/unimport/pull/15 and https://github.com/unjs/unimport/pull/72
  vueTemplate: false,

  // Custom resolvers, compatible with `unplugin-vue-components`
  // see https://github.com/antfu/unplugin-auto-import/pull/23/
  resolvers: [
    /* ... */
  ],

  // Inject the imports at the end of other imports
  injectAtEnd: true,

  // Generate corresponding .eslintrc-auto-import.json file.
  // eslint globals Docs - https://eslint.org/docs/user-guide/configuring/language-options#specifying-globals
  eslintrc: {
    enabled: false, // Default `false`
    filepath: './.eslintrc-auto-import.json', // Default `./.eslintrc-auto-import.json`
    globalsPropValue: true, // Default `true`, (true | false | 'readonly' | 'readable' | 'writable' | 'writeable')
  },
})

上面的配置很完整,但我们一般关注其中几个就可以了。

import:配置自动导入规则

使用预设

对于一些常见的库,插件已经内置了它的自动导入规则,如:vue、vue-router、pinia、react 等。

在 imports 数组里添加字符串就代表使用预设:

AutoImport({
  imports: ["vue", "vue-router", "pinia"],
}

自动引入第三方库

有些库没有预设,我们也想自动导入该怎么办?比如 axios、loadsh、vueuse。

使用对象语法,自定义导入规则:包名: 数组

AutoImport({
  imports: [
    "vue",
    // 自定义导入规则
    {
      '包名 ikun': [
        // 命名导入,相当于会自动添加 import { sing } from "ikun";
        'sing',
        // 设置别名导入,自动添加 import { sing as singFromIkun } from "ikun";
        ['sing', 'singFromIkun'],
      ],
    },
  ]
})

注意:对于默认导出的库,export default,自定义导入规则要写成别名导入的形式,导入的字段为 default。

比如 axios,我们正常使用是这样导入:

import axios from "axios"

因为 axios 库是 export default 默认导出的,所以我们不会 import { axios } from "axios";
对于这种默认导出,AutoImport 自动导入规则要写成别名导入:

AutoImport({
  imports: [
    "vue",
    // 自定义导入规则
    {
      '包名 ikun': [
        // 命名导入,相当于会自动添加 import { sing } from "ikun";
        'sing',
        // 设置别名导入,自动添加 import { sing as singFromIkun } from "ikun";
        ['sing', 'singFromIkun'],
      ],
      'axios': [
        // default imports
        ['default', 'axios'], // import { default as axios } from 'axios',
      ],
    },
  ]
})

说白了,压根没有import axios from "axios";的写法,它只是import { default as axios} from "axios";的语法糖。因此在这种编译配置的情况下,需要严格按照规范来定义。

补充一个自动导入 vueuse:

AutoImport({
  imports: [
    "vue",
    {
      '@vueuse/core': [
        // named imports
        'useMouse', // import { useMouse } from '@vueuse/core',
        // alias
        ['useFetch', 'useMyFetch'], // import { useFetch as useMyFetch } from '@vueuse/core',
      ]
    }
  ]
})

自动导入 TypeScript 类型

上面都是 js 引入,如果是在 ts 中这样引入,会没有类型,vue-tsc 类型检查过不了,build 构建失败。

导入 ts 类型的规则:

{
  from: 'vue-router',
  imports: ['RouteLocationRaw'],
  type: true,
}

其实上面这种写法才是导入规则的完整写法包名: 数组字符串这些都是简写,就和 webpack loader 配置一样。
这个对象就是在模拟import { xxx } from "xxx";,多了一个 type 为 true,就是标明了导入的为类型,等价于:import type { Xxx as Hhh} from "xxx";

这时候就要注意 type 的位置了:

AutoImport({
  imports: [
    "vue",
    // {
    //     axios: ["default", "axios"]
    // },
    {
      from: "axios",
      imports: [["default", "axios"], "AxiosStatic"],
      type: true
    }
  ],
})

如上述写法就是错误的,它编译后就是:

import type { default as axios, AxiosStatic} from "axios";

显然 axios 不是类型,正确写法应该是:

import { default as axios, type AxiosStatic} from "axios";

那怎么把 type 和 AxiosStatic 类型绑定到一起,编译出正确的 import 语句呢?

AxiosStatic 继续写成对象形式即可:

AutoImport({
  imports: [
    // {
    //     axios: ["default", "axios"]
    // },
    // {
    //     from: "axios",
    //     imports: [["default", "axios"], "AxiosStatic"],
    //     type: true
    // }
    {
      from: "axios",
      imports: [ ["default", "axios"], {
          name: "AxiosStatic",
          type: true
        }],
    } 
  ]
})

vue 预设的自动导入配置

可以看到 vue 自动导入配置的预设,内部写法就是如上诉一样:

{
     "from": "vue",
     "imports": [
          "EffectScope",
          "computed",
          "createApp",
          "customRef",
          "defineAsyncComponent",
          "defineComponent",
          "effectScope",
          "getCurrentInstance",
          "getCurrentScope",
          "h",
          "inject",
          "isProxy",
          "isReactive",
          "isReadonly",
          "isRef",
          "markRaw",
          "nextTick",
          "onActivated",
          "onBeforeMount",
          "onBeforeUnmount",
          "onBeforeUpdate",
          "onDeactivated",
          "onErrorCaptured",
          "onMounted",
          "onRenderTracked",
          "onRenderTriggered",
          "onScopeDispose",
          "onServerPrefetch",
          "onUnmounted",
          "onUpdated",
          "provide",
          "reactive",
          "readonly",
          "ref",
          "resolveComponent",
          "shallowReactive",
          "shallowReadonly",
          "shallowRef",
          "toRaw",
          "toRef",
          "toRefs",
          "toValue",
          "triggerRef",
          "unref",
          "useAttrs",
          "useCssModule",
          "useCssVars",
          "useSlots",
          "watch",
          "watchEffect",
          "watchPostEffect",
          "watchSyncEffect",
          {
               "name": "Component",
               "type": true
          },
          {
               "name": "ComponentPublicInstance",
               "type": true
          },
          {
               "name": "ComputedRef",
               "type": true
          },
          {
               "name": "ExtractDefaultPropTypes",
               "type": true
          },
          {
               "name": "ExtractPropTypes",
               "type": true
          },
          {
               "name": "ExtractPublicPropTypes",
               "type": true
          },
          {
               "name": "InjectionKey",
               "type": true
          },
          {
               "name": "PropType",
               "type": true
          },
          {
               "name": "Ref",
               "type": true
          },
          {
               "name": "VNode",
               "type": true
          },
          {
               "name": "WritableComputedRef",
               "type": true
          }
     ]
}

dts:让编辑器环境识别 ts 类型

配置 import 后能自动导入 ts 类型了,但那是在编译时才会导入,在 vscode 编辑器里写代码时,类型可没导入。在 ts 看来,你使用了未定义的变量,会报错。

这其实就和之前按需引入 elmessage 的问题一样:
按需引入 ElMessage,没有样式且类型检查失败

这时就需要对自动导入的内容进行类型声明:

AutoImport({
  dts: true // or a custom path
})

开启dts配置后,就会自动生成auto-imports.d.ts文件,进行全局类型声明。默认生成在根目录。
另外要确保tsconfig.json中 include 配置项包含了这个类型声明文件,好让 ts 读取里面的类型。

各种开源组件库按需引入的时候,就默认就打开了这个配置,所以根目录会出现这么个文件。

上面 axios 配置,自动生成的类型声明:

/* eslint-disable */
/* prettier-ignore */
// @ts-nocheck
// noinspection JSUnusedGlobalSymbols
// Generated by unplugin-auto-import
export {}
declare global {
  const axios: typeof import('axios')['default']
}
// for type re-export
declare global {
  // @ts-ignore
  export type { AxiosStatic } from 'axios'
}

eslintrc:解决 eslint 检查错误

ts 通过了禁止使用未定义变量的检查,但 eslint 检查未通过。eslint 的检查中也会认为你使用了未定义的变量。解决办法自然是在 eslint 的配置中声明一下这些是全局变量,可以未导入直接用。

unplugin 官方认为如果使用了 ts,就不必再让 eslint 来检查是否使用未定义的变量了,建议把no-undef这条规则关掉。

💡 When using TypeScript, we recommend to disable no-undef rule directly as TypeScript already check for them and you don’t need to worry about this.

如果开着双重保险,就要让 eslint 识别自动导入的内容为全局变量:

  1. 开启配置,在项目根目录生成全局变量文件 .eslintrc-auto-import.json
AutoImport({
  eslintrc: {
    enabled: true, // <-- this
  },
})
{
  "globals": {
    "AxiosStatic": true,
    "axios": true
  }
}

  1. 在 eslint 校验规则中继承它。
// .eslintrc.js
module.exports = {
  extends: [
    './.eslintrc-auto-import.json',
  ],
}

dirs:配置本地目录文件自动导入

比如项目中有一个 utils 文件夹,如果想自动引入里面的文件,则可以用 dirs 来配置

AutoImport({
 	// Auto import for module exports under directories
  // by default it only scan one level of modules under the directory
  dirs: [
    // './hooks',
    // './composables' // only root modules
    // './composables/**', // all nested modules
    // ...
    "./src/utils/**"
  ]
})

unplugin-vue-components

https://github.com/unplugin/unplugin-vue-components

unplugin-vue-components 这玩意是用来专门引入 vue SFC 文件的,相当于 unplugin-auot-import 的一个子集。作者都是 antfu。

基本使用

// vite.config.ts
import Components from 'unplugin-vue-components/vite'

export default defineConfig({
  plugins: [
    Components({ /* options */ }),
  ],
})
// webpack.config.js & vue.config.js
module.exports = {
  /* ... */
  plugins: [
    require('unplugin-vue-components/webpack').default({ /* options */ }),
  ],
}
Components({
  // relative paths to the directory to search for components.
  dirs: ['src/components'],

  // valid file extensions for components.
  extensions: ['vue'],

  // Glob patterns to match file names to be detected as components.
  // When specified, the `dirs` and `extensions` options will be ignored.
  globs: ['src/components/*.{vue}'],

  // search for subdirectories
  deep: true,

  // resolvers for custom components
  resolvers: [],

  // generate `components.d.ts` global declarations,
  // also accepts a path for custom filename
  // default: `true` if package typescript is installed
  dts: false,

  // Allow subdirectories as namespace prefix for components.
  directoryAsNamespace: false,

  // Collapse same prefixes (camel-sensitive) of folders and components
  // to prevent duplication inside namespaced component name.
  // works when `directoryAsNamespace: true`
  collapseSamePrefixes: false,

  // Subdirectory paths for ignoring namespace prefixes.
  // works when `directoryAsNamespace: true`
  globalNamespaces: [],

  // auto import for directives
  // default: `true` for Vue 3, `false` for Vue 2
  // Babel is needed to do the transformation for Vue 2, it's disabled by default for performance concerns.
  // To install Babel, run: `npm install -D @babel/parser`
  directives: true,

  // Transform path before resolving
  importPathTransform: v => v,

  // Allow for components to override other components with the same name
  allowOverrides: false,

  // filters for transforming targets
  include: [/\.vue$/, /\.vue\?vue/],
  exclude: [/[\\/]node_modules[\\/]/, /[\\/]\.git[\\/]/, /[\\/]\.nuxt[\\/]/],

  // Vue version of project. It will detect automatically if not specified.
  // Acceptable value: 2 | 2.7 | 3
  version: 2.7,

  // Only provide types of components in library (registered globally)
  types: []
})

导入流行库组件

该插件内置了大多数流行库解析器,可以直接开箱即用。
并且会在根目录生成一个ui库组件以及指令路径components.d.ts文件

// vite.config.js
import { defineConfig } from 'vite'
import Components from 'unplugin-vue-components/vite'
import {
  ElementPlusResolver,
  AntDesignVueResolver,
  VantResolver,
  HeadlessUiResolver,
  ElementUiResolver
} from 'unplugin-vue-components/resolvers'

export default defineConfig({
  plugins: [
    Components({
      // ui库解析器,也可以自定义
      resolvers: [
        ElementPlusResolver(),
        AntDesignVueResolver(),
        VantResolver(),
        HeadlessUiResolver(),
        ElementUiResolver()
      ]
    })
  ]
})

/* eslint-disable */
/* prettier-ignore */
// @ts-nocheck
// Generated by unplugin-vue-components
// Read more: https://github.com/vuejs/core/pull/3399
export {}

declare module 'vue' {
  export interface GlobalComponents {
    ABreadcrumb: typeof import('ant-design-vue/es')['Breadcrumb']
    AButton: typeof import('ant-design-vue/es')['Button']
    RouterLink: typeof import('vue-router')['RouterLink']
    RouterView: typeof import('vue-router')['RouterView']
    SvgIcon: typeof import('./src/components/SvgIcon/index.vue')['default']
    SwitchTheme: typeof import('./src/components/SwitchTheme/SwitchTheme.vue')['default']
  }
}

自动引入自己的本地组件

默认情况下,自己写的组件放在src/components路径下是会被自动引入的。
比如上面 components.d.ts 文件中的 SvgIcon 和 SwitchTheme 就是自己写的组件。

当然,也可以进一步配置自动引入的情况:

// vite.config.js
import { defineConfig } from 'vite'
import Components from 'unplugin-vue-components/vite'

export default defineConfig({
  plugins: [
    Components({
      // 指定组件位置,默认是src/components
      dirs: ['src/components'],
      // ui库解析器
      // resolvers: [ElementPlusResolver()],
      extensions: ['vue'],
      // 配置文件生成位置
      dts: 'src/components.d.ts'
    })
  ]
})

自定义解析器 resolvers,实现组件库按需导入

如果是自己开发的组件库,为了让它支持自动按需导入,就需要自己编写解析器。

Components({
  resolvers: [
    // example of importing Vant
    (componentName) => {
      // where `componentName` is always CapitalCase
      if (componentName.startsWith('Van'))
        return { name: componentName.slice(3), from: 'vant' }
    },
  ],
})

resolvers 数组里可以传入一个函数,这个函数会在编译时不断执行。
函数接收组件名,并返回一个和 unplugin-auto-import 插件中 imports 配置一样的配置对象,这个对象就是 import 语句的描述对象,最终依据它生成导入语句。

  • 注意:组件名会自动转成大驼峰写法。

因此所谓的解析器,功能就是根据组件名映射成 import 导入语句。

假设组件库的前缀为 ikun,比如按钮组件: ikun-button

  1. 在 SFC 中使用了组件
<!-- 在 SFC 中使用了组件 -->
<ikun-button>按钮</ikun-button>
  1. 解析器中都能拿到大驼峰格式的组件名
const IkunResolver = componentName => {
    console.log(componentName) // IkunButton

    // 组件名有很多,通过前缀过滤出本组件库的组件名
    if (componentName.startsWith("Ikun")) {
        // import 引入规则对象:
        // 等价于 import { IkunButton } from "ikun-ui";
        return {
            name: componentName,
            from: "ikun-ui"
        }
    }
    return null
}
  1. 使用组件库的 resolver
Components({
  resolvers: [
    IkunResolver()
  ],
})

还有一个细节问题:组件库中组件的样式可能是单独一个文件的,不一定在 .vue 文件中。
比如这样:

ikun-button
|
|—— style
|		|—— index.css
|			
|—— index.vue

上面的 import 配置对象写法只会引入 SFC 文件,并不会引入样式文件。

解决办法:副作用配置项。引入组件的副作用是会引入另一个文件,我们让这个文件是样式文件。

  • sideEffects
const IkunResolver = componentName => {
    if (componentName.startsWith("Ikun")) {
        // 等价于:
        // import { IkunButton } from "ikun-ui";
        // import "ikun-ui/ikun-button/style/index.css";
        return {
            name: componentName,
            from: "ikun-ui",
            sideEffects: `ikun-ui/${componentName}/style/index.css`
        }
    }
    return null
}

开源库的解析器写法(参考)

element-plus

// src/core/resolvers/element-plus.ts
function getSideEffectsLegacy(partialName, options) {
  const { importStyle } = options;
  if (!importStyle)
    return;
  if (importStyle === "sass") {
    return [
      "element-plus/packages/theme-chalk/src/base.scss",
      `element-plus/packages/theme-chalk/src/${partialName}.scss`
    ];
  } else if (importStyle === true || importStyle === "css") {
    return [
      "element-plus/lib/theme-chalk/base.css",
      `element-plus/lib/theme-chalk/el-${partialName}.css`
    ];
  }
}
function getSideEffects2(dirName, options) {
  const { importStyle, ssr, nightly } = options;
  const themeFolder = nightly ? "@element-plus/nightly/theme-chalk" : "element-plus/theme-chalk";
  const esComponentsFolder = nightly ? "@element-plus/nightly/es/components" : "element-plus/es/components";
  if (importStyle === "sass") {
    return ssr ? [`${themeFolder}/src/base.scss`, `${themeFolder}/src/${dirName}.scss`] : [`${esComponentsFolder}/base/style/index`, `${esComponentsFolder}/${dirName}/style/index`];
  } else if (importStyle === true || importStyle === "css") {
    return ssr ? [`${themeFolder}/base.css`, `${themeFolder}/el-${dirName}.css`] : [`${esComponentsFolder}/base/style/css`, `${esComponentsFolder}/${dirName}/style/css`];
  }
}
function resolveComponent(name, options) {
  if (options.exclude && name.match(options.exclude))
    return;
  if (!name.match(/^El[A-Z]/))
    return;
  if (name.match(/^ElIcon.+/)) {
    return {
      name: name.replace(/^ElIcon/, ""),
      from: "@element-plus/icons-vue"
    };
  }
  const partialName = kebabCase(name.slice(2));
  const { version, ssr, nightly } = options;
  if (compare(version, "1.1.0-beta.1", ">=") || nightly) {
    return {
      name,
      from: `${nightly ? "@element-plus/nightly" : "element-plus"}/${ssr ? "lib" : "es"}`,
      sideEffects: getSideEffects2(partialName, options)
    };
  } else if (compare(version, "1.0.2-beta.28", ">=")) {
    return {
      from: `element-plus/es/el-${partialName}`,
      sideEffects: getSideEffectsLegacy(partialName, options)
    };
  } else {
    return {
      from: `element-plus/lib/el-${partialName}`,
      sideEffects: getSideEffectsLegacy(partialName, options)
    };
  }
}
function resolveDirective(name, options) {
  if (!options.directives)
    return;
  const directives2 = {
    Loading: { importName: "ElLoadingDirective", styleName: "loading" },
    Popover: { importName: "ElPopoverDirective", styleName: "popover" },
    InfiniteScroll: { importName: "ElInfiniteScroll", styleName: "infinite-scroll" }
  };
  const directive = directives2[name];
  if (!directive)
    return;
  const { version, ssr, nightly } = options;
  if (compare(version, "1.1.0-beta.1", ">=") || nightly) {
    return {
      name: directive.importName,
      from: `${nightly ? "@element-plus/nightly" : "element-plus"}/${ssr ? "lib" : "es"}`,
      sideEffects: getSideEffects2(directive.styleName, options)
    };
  }
}
var noStylesComponents = ["ElAutoResizer"];
function ElementPlusResolver(options = {}) {
  let optionsResolved;
  async function resolveOptions() {
    if (optionsResolved)
      return optionsResolved;
    optionsResolved = __spreadValues({
      ssr: false,
      version: await getPkgVersion("element-plus", "2.2.2"),
      importStyle: "css",
      directives: true,
      exclude: void 0,
      noStylesComponents: options.noStylesComponents || [],
      nightly: false
    }, options);
    return optionsResolved;
  }
  return [
    {
      type: "component",
      resolve: async (name) => {
        const options2 = await resolveOptions();
        if ([...options2.noStylesComponents, ...noStylesComponents].includes(name))
          return resolveComponent(name, __spreadProps(__spreadValues({}, options2), { importStyle: false }));
        else
          return resolveComponent(name, options2);
      }
    },
    {
      type: "directive",
      resolve: async (name) => {
        return resolveDirective(name, await resolveOptions());
      }
    }
  ];
}

vant

// src/core/resolvers/vant.ts
var moduleType = isSSR ? "lib" : "es";
function getSideEffects4(dirName, options) {
  const { importStyle = true } = options;
  if (!importStyle || isSSR)
    return;
  if (importStyle === "less")
    return `vant/${moduleType}/${dirName}/style/less`;
  if (importStyle === "css")
    return `vant/${moduleType}/${dirName}/style/index`;
  return `vant/${moduleType}/${dirName}/style/index`;
}
function VantResolver(options = {}) {
  return {
    type: "component",
    resolve: (name) => {
      if (name.startsWith("Van")) {
        const partialName = name.slice(3);
        return {
          name: partialName,
          from: `vant/${moduleType}`,
          sideEffects: getSideEffects4(kebabCase(partialName), options)
        };
      }
    }
  };
}
文章来源:https://blog.csdn.net/qq_43220213/article/details/135141942
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