@vue/component-compiler-utils

What is @vue/component-compiler-utils?

The @vue/component-compiler-utils package is a lower-level utility for compiling Vue single-file components (SFCs). It is used by higher-level tools like vue-loader to process the various parts of a Vue component, such as the template, script, and styles. It provides functions to parse SFCs, compile their templates to render functions, and scope their styles.

What are @vue/component-compiler-utils's main functionalities?

Parsing Single-File Components

This feature allows you to parse .vue files into an object descriptor that contains separate objects for template, script, styles, and custom blocks.

const { parse } = require('@vue/component-compiler-utils');
const { readFileSync } = require('fs');

const source = readFileSync('MyComponent.vue', 'utf-8');
const descriptor = parse({
  source,
  filename: 'MyComponent.vue',
  compiler: require('vue-template-compiler')
});

Compiling Template

This feature compiles the template part of a Vue component into a JavaScript render function.

const { compileTemplate } = require('@vue/component-compiler-utils');
const { descriptor } = require('./parsed-component');

const compiled = compileTemplate({
  source: descriptor.template.content,
  filename: 'MyComponent.vue',
  compiler: require('vue-template-compiler')
});

Scoping Styles

This feature processes the styles of a Vue component, adding scope IDs to make them unique to the component, which helps in preventing style leakage.

const { compileStyle, compileStyleAsync } = require('@vue/component-compiler-utils');
const { descriptor } = require('./parsed-component');

const compiledStyle = compileStyle({
  source: descriptor.styles[0].content,
  filename: 'MyComponent.vue',
  id: 'data-v-12345678',
  scoped: true
});

Other packages similar to @vue/component-compiler-utils

vue-template-compiler

This package is used to compile Vue 2.0 templates into render functions. It is often used in conjunction with @vue/component-compiler-utils but focuses solely on template compilation.

vue-loader

Vue-loader is a webpack loader that allows you to write Vue components in a format called Single-File Components (SFCs). It uses @vue/component-compiler-utils under the hood to process the various parts of a Vue component.

rollup-plugin-vue

This is a Rollup plugin that integrates Vue SFC compilation into Rollup builds. Similar to vue-loader, it handles the processing of Vue components but is tailored for Rollup instead of webpack.

README

@vue/component-compiler-utils

Lower level utilities for compiling Vue single file components

This package contains lower level utilities that you can use if you are writing a plugin / transform for a bundler or module system that compiles Vue single file components into JavaScript. It is used in vue-loader version 15 and above.

The API surface is intentionally minimal - the goal is to reuse as much as possible while being as flexible as possible.

Why isn't vue-template-compiler a peerDependency?

Since this package is more often used as a low-level utility, it is usually a transitive dependency in an actual Vue project. It is therefore the responsibility of the higher-level package (e.g. vue-loader) to inject vue-template-compiler via options when calling the parse and compileTemplate methods.

Not listing it as a peer depedency also allows tooling authors to use a non-default template compiler instead of vue-template-compiler without having to include it just to fullfil the peer dep requirement.

API

parse(ParseOptions): SFCDescriptor

Parse raw single file component source into a descriptor with source maps. The actual compiler (vue-template-compiler) must be passed in via the compiler option so that the specific version used can be determined by the end user.

interface ParseOptions {
  source: string
  filename?: string
  compiler: VueTemplateCompiler
  // https://github.com/vuejs/vue/tree/dev/packages/vue-template-compiler#compilerparsecomponentfile-options
  // default: { pad: 'line' }
  compilerParseOptions?: VueTemplateCompilerParseOptions
  sourceRoot?: string
  needMap?: boolean
}

interface SFCDescriptor {
  template: SFCBlock | null
  script: SFCBlock | null
  styles: SFCBlock[]
  customBlocks: SFCCustomBlock[]
}

interface SFCCustomBlock {
  type: string
  content: string
  attrs: { [key: string]: string | true }
  start: number
  end: number
  map?: RawSourceMap
}

interface SFCBlock extends SFCCustomBlock {
  lang?: string
  src?: string
  scoped?: boolean
  module?: string | boolean
}

compileTemplate(TemplateCompileOptions): TemplateCompileResults

Takes raw template source and compile it into JavaScript code. The actual compiler (vue-template-compiler) must be passed in via the compiler option so that the specific version used can be determined by the end user.

It can also optionally perform pre-processing for any templating engine supported by consolidate.

interface TemplateCompileOptions {
  source: string
  filename: string

  compiler: VueTemplateCompiler
  // https://github.com/vuejs/vue/tree/dev/packages/vue-template-compiler#compilercompiletemplate-options
  // default: {}
  compilerOptions?: VueTemplateCompilerOptions

  // Template preprocessor
  preprocessLang?: string
  preprocessOptions?: any

  // Transform asset urls found in the template into `require()` calls
  // This is off by default. If set to true, the default value is
  // {
  //   audio: 'src',
  //   video: ['src', 'poster'],
  //   source: 'src',
  //   img: 'src',
  //   image: ['xlink:href', 'href'],
  //   use: ['xlink:href', 'href']
  // }
  transformAssetUrls?: AssetURLOptions | boolean

  // For vue-template-es2015-compiler, which is a fork of Buble
  transpileOptions?: any

  isProduction?: boolean  // default: false
  isFunctional?: boolean  // default: false
  optimizeSSR?: boolean   // default: false

  // Whether prettify compiled render function or not (development only)
  // default: true
  prettify?: boolean
}

interface TemplateCompileResult {
  ast: Object | undefined
  code: string
  source: string
  tips: string[]
  errors: string[]
}

interface AssetURLOptions {
  [name: string]: string | string[]
}

Handling the Output

The resulting JavaScript code will look like this:

var render = function (h) { /* ... */}
var staticRenderFns = [function (h) { /* ... */}, function (h) { /* ... */}]

It does NOT assume any module system. It is your responsibility to handle the exports, if needed.

compileStyle(StyleCompileOptions)

Take input raw CSS and applies scoped CSS transform. It does NOT handle pre-processors. If the component doesn't use scoped CSS then this step can be skipped.

interface StyleCompileOptions {
  source: string
  filename: string
  id: string
  map?: any
  scoped?: boolean
  trim?: boolean
  preprocessLang?: string
  preprocessOptions?: any
  postcssOptions?: any
  postcssPlugins?: any[]
}

interface StyleCompileResults {
  code: string
  map: any | void
  rawResult: LazyResult | void // raw lazy result from PostCSS
  errors: string[]
}

compileStyleAsync(StyleCompileOptions)

Same as compileStyle(StyleCompileOptions) but it returns a Promise resolving to StyleCompileResults. It can be used with async postcss plugins.