feat: add vue-cli3 source

Author: KuangPF

packages/@vue/babel-preset-app/.npmignore

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+__tests__
+__mocks__

packages/@vue/babel-preset-app/README.md

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+# @vue/babel-preset-app
+
+This is the default Babel preset used in all Vue CLI projects. **Note: this preset is meant to be used exclusively in projects created via Vue CLI and does not consider external use cases.**
+
+## Included Features
+
+### [@babel/preset-env](https://new.babeljs.io/docs/en/next/babel-preset-env.html)
+
+`preset-env` automatically determines the transforms and polyfills to apply based on your browser target. See [Browser Compatibility](https://cli.vuejs.org/guide/browser-compatibility.html) section in docs for more details.
+
+- `modules: false`
+  - auto set to `'commonjs'` in Jest tests
+- [`useBuiltIns: 'usage'`](#usebuiltins)
+- `targets` is determined:
+  - using `browserslist` field in `package.json` when building for browsers
+  - set to `{ node: 'current' }` when running unit tests in Node.js
+- Includes `Promise` polyfill by default so that they are usable even in non-transpiled dependencies (only for environments that need it)
+
+### Stage 3 or Below
+
+Only the following stage 3 or below features are supported (object reset spread is supported as part of `preset-env`):
+
+- [Dynamic Import Syntax](https://github.com/tc39/proposal-dynamic-import)
+- [Proposal Class Properties](https://babeljs.io/docs/en/next/babel-plugin-proposal-class-properties.html)
+- [Proposal Decorators (legacy)](https://babeljs.io/docs/en/next/babel-plugin-proposal-decorators.html)
+
+If you need additional stage 3 or below features, you need to install and configure it yourself.
+
+### Vue JSX support
+
+- [@babel/plugin-syntax-jsx](https://github.com/babel/babel/tree/master/packages/babel-plugin-syntax-jsx)
+- [babel-plugin-transform-vue-jsx](https://github.com/vuejs/babel-plugin-transform-vue-jsx)
+- ~~[babel-plugin-jsx-event-modifiers](https://github.com/nickmessing/babel-plugin-jsx-event-modifiers)~~ (temporarily disabled until fixed for Babel 7)
+- ~~[babel-plugin-jsx-v-model](https://github.com/nickmessing/babel-plugin-jsx-v-model)~~ (temporarily disabled until fixed for Babel 7)
+
+### [@babel/plugin-transform-runtime](https://github.com/babel/babel/tree/master/packages/babel-plugin-transform-runtime)
+
+`transform-runtime` avoids inlining helpers in every file. This is enabled for helpers only, since polyfills are handled by `babel-preset-env`.
+
+## Options
+
+- All options from [@babel/preset-env](https://babeljs.io/docs/en/next/babel-preset-env.html) are supported, with some of them having smarter defaults.
+
+### modules
+
+- Default:
+  - `false` when building with webpack
+  - `'commonjs'` when running tests in Jest.
+
+Explicitly set `modules` option for `babel-preset-env`. See [babel-preset-env docs](https://github.com/babel/babel/tree/master/packages/babel-preset-env#modules) for more details.
+
+### targets
+
+- Default:
+  - determined from `browserslist` field in `package.json` when building for browsers
+  - set to `{ node: 'current' }` when running unit tests in Node.js
+
+Explicitly set `targets` option for `babel-preset-env`. See [babel-preset-env docs](https://github.com/babel/babel/tree/master/packages/babel-preset-env#targets) for more details.
+
+### useBuiltIns
+
+- Default: `'usage'`
+- Allowed values: `'usage' | 'entry' | false`
+
+Explicitly set `useBuiltIns` option for `babel-preset-env`.
+
+The default value is `'usage'`, which adds imports to polyfills based on the usage in transpiled code. For example, if you use `Object.assign` in your code, the corresponding polyfill will be auto-imported if your target environment does not supports it.
+
+If you are building a library or web component instead of an app, you probably want to set this to `false` and let the consuming app be responsible for the polyfills.
+
+Note that the usage detection does not apply to your dependencies (which are excluded by `cli-plugin-babel` by default). If one of your dependencies need polyfills, you have a few options:
+
+1. **If the dependency is written in an ES version that your target environments do not support:** Add that dependency to the `transpileDependencies` option in `vue.config.js`. This would enable both syntax transforms and usage-based polyfill detection for that dependency.
+
+2. **If the dependency ships ES5 code and explicitly lists the polyfills needed:** you can pre-include the needed polyfills using the [polyfills](#polyfills) option for this preset.
+
+3. **If the dependency ships ES5 code, but uses ES6+ features without explicitly listing polyfill requirements (e.g. Vuetify):** Use `useBuiltIns: 'entry'` and then add `import '@babel/polyfill'` to your entry file. This will import **ALL** polyfills based on your `browserslist` targets so that you don't need to worry about dependency polyfills anymore, but will likely increase your final bundle size with some unused polyfills.
+
+See [@babel/preset-env docs](https://new.babeljs.io/docs/en/next/babel-preset-env.html#usebuiltins-usage) for more details.
+
+### polyfills
+
+- Default: `['es6.array.iterator', 'es6.promise', 'es7.promise.finally']`
+
+A list of [core-js](https://github.com/zloirock/core-js) polyfills to pre-include when using `useBuiltIns: 'usage'`. **These polyfills are automatically excluded if they are not needed for your target environments**.
+
+Use this option when you have 3rd party dependencies that are not processed by Babel but have specific polyfill requirements (e.g. Axios and Vuex require Promise support).
+
+### jsx
+
+- Default: `true`.
+
+Set to `false` to disable JSX support.
+
+### loose
+
+- Default: `false`.
+
+Setting this to `true` will generate code that is more performant but less spec-compliant.

packages/@vue/babel-preset-app/__tests__/babel-preset.spec.js

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+const babel = require('@babel/core')
+const preset = require('../index')
+const defaultOptions = {
+  babelrc: false,
+  presets: [preset]
+}
+
+test('polyfill detection', () => {
+  let { code } = babel.transformSync(`
+    const a = new Map()
+  `.trim(), {
+    babelrc: false,
+    presets: [[preset, {
+      targets: { node: 'current' }
+    }]]
+  })
+  // default includes
+  expect(code).not.toMatch(`import "core-js/modules/es6.promise"`)
+  // usage-based detection
+  expect(code).not.toMatch(`import "core-js/modules/es6.map"`)
+
+  ;({ code } = babel.transformSync(`
+    const a = new Map()
+  `.trim(), {
+    babelrc: false,
+    presets: [[preset, {
+      targets: { ie: 9 }
+    }]]
+  }))
+  // default includes
+  expect(code).toMatch(`import "core-js/modules/es6.promise"`)
+  // promise polyfill alone doesn't work in IE, needs this as well. fix: #1642
+  expect(code).toMatch(`import "core-js/modules/es6.array.iterator"`)
+  // usage-based detection
+  expect(code).toMatch(`import "core-js/modules/es6.map"`)
+})
+
+test('modern mode always skips polyfills', () => {
+  process.env.VUE_CLI_MODERN_BUILD = true
+  let { code } = babel.transformSync(`
+    const a = new Map()
+  `.trim(), {
+    babelrc: false,
+    presets: [[preset, {
+      targets: { ie: 9 },
+      useBuiltIns: 'usage'
+    }]]
+  })
+  // default includes
+  expect(code).not.toMatch(`import "core-js/modules/es6.promise"`)
+  // usage-based detection
+  expect(code).not.toMatch(`import "core-js/modules/es6.map"`)
+
+  ;({ code } = babel.transformSync(`
+    const a = new Map()
+  `.trim(), {
+    babelrc: false,
+    presets: [[preset, {
+      targets: { ie: 9 },
+      useBuiltIns: 'entry'
+    }]]
+  }))
+  // default includes
+  expect(code).not.toMatch(`import "core-js/modules/es6.promise"`)
+  // usage-based detection
+  expect(code).not.toMatch(`import "core-js/modules/es6.map"`)
+  delete process.env.VUE_CLI_MODERN_BUILD
+})
+
+test('object spread', () => {
+  const { code } = babel.transformSync(`
+    const a = { ...b }
+  `.trim(), defaultOptions)
+  expect(code).toMatch(`import _objectSpread from`)
+  expect(code).toMatch(`var a = _objectSpread({}, b)`)
+})
+
+test('dynamic import', () => {
+  expect(() => {
+    babel.transformSync(`const Foo = () => import('./Foo.vue')`, defaultOptions)
+  }).not.toThrow()
+})
+
+test('async/await', () => {
+  const { code } = babel.transformSync(`
+    async function hello () {
+      await Promise.resolve()
+    }
+    hello()
+  `.trim(), defaultOptions)
+  expect(code).toMatch(`import "core-js/modules/es6.promise"`)
+  // should use regenerator runtime
+  expect(code).toMatch(`import "regenerator-runtime/runtime"`)
+  // should use required helper instead of inline
+  expect(code).toMatch(/@babel.*runtime\/helpers\/.*asyncToGenerator/)
+})
+
+test('jsx', () => {
+  const { code } = babel.transformSync(`
+    export default {
+      render () {
+        return <div>bar</div>
+      }
+    }
+  `.trim(), defaultOptions)
+  expect(code).toMatch(`var h = arguments[0]`)
+  expect(code).toMatch(`return h("div", ["bar"])`)
+})

packages/@vue/babel-preset-app/index.js

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+const path = require('path')
+
+const defaultPolyfills = [
+  // promise polyfill alone doesn't work in IE,
+  // needs this as well. see: #1642
+  'es6.array.iterator',
+  // this is required for webpack code splitting, vuex etc.
+  'es6.promise',
+  // #2012 es6.promise replaces native Promise in FF and causes missing finally
+  'es7.promise.finally'
+]
+
+function getPolyfills (targets, includes, { ignoreBrowserslistConfig, configPath }) {
+  const { isPluginRequired } = require('@babel/preset-env')
+  const builtInsList = require('@babel/preset-env/data/built-ins.json')
+  const getTargets = require('@babel/preset-env/lib/targets-parser').default
+  const builtInTargets = getTargets(targets, {
+    ignoreBrowserslistConfig,
+    configPath
+  })
+
+  return includes.filter(item => {
+    return isPluginRequired(builtInTargets, builtInsList[item])
+  })
+}
+
+module.exports = (context, options = {}) => {
+  const presets = []
+  const plugins = []
+
+  // JSX
+  if (options.jsx !== false) {
+    plugins.push(
+      require('@babel/plugin-syntax-jsx'),
+      require('babel-plugin-transform-vue-jsx')
+      // require('babel-plugin-jsx-event-modifiers'),
+      // require('babel-plugin-jsx-v-model')
+    )
+  }
+
+  const {
+    polyfills: userPolyfills,
+    loose = false,
+    debug = false,
+    useBuiltIns = 'usage',
+    modules = false,
+    targets: rawTargets,
+    spec,
+    ignoreBrowserslistConfig = !!process.env.VUE_CLI_MODERN_BUILD,
+    configPath,
+    include,
+    exclude,
+    shippedProposals,
+    forceAllTransforms,
+    decoratorsLegacy
+  } = options
+
+  // resolve targets
+  let targets
+  if (process.env.VUE_CLI_BABEL_TARGET_NODE) {
+    // running tests in Node.js
+    targets = { node: 'current' }
+  } else if (process.env.VUE_CLI_BUILD_TARGET === 'wc' || process.env.VUE_CLI_BUILD_TARGET === 'wc-async') {
+    // targeting browsers that at least support ES2015 classes
+    // https://github.com/babel/babel/blob/master/packages/babel-preset-env/data/plugins.json#L52-L61
+    targets = {
+      browsers: [
+        'Chrome >= 49',
+        'Firefox >= 45',
+        'Safari >= 10',
+        'Edge >= 13',
+        'iOS >= 10',
+        'Electron >= 0.36'
+      ]
+    }
+  } else if (process.env.VUE_CLI_MODERN_BUILD) {
+    // targeting browsers that support <script type="module">
+    targets = { esmodules: true }
+  } else {
+    targets = rawTargets
+  }
+
+  // included-by-default polyfills. These are common polyfills that 3rd party
+  // dependencies may rely on (e.g. Vuex relies on Promise), but since with
+  // useBuiltIns: 'usage' we won't be running Babel on these deps, they need to
+  // be force-included.
+  let polyfills
+  const buildTarget = process.env.VUE_CLI_BUILD_TARGET || 'app'
+  if (
+    buildTarget === 'app' &&
+    useBuiltIns === 'usage' &&
+    !process.env.VUE_CLI_BABEL_TARGET_NODE &&
+    !process.env.VUE_CLI_MODERN_BUILD
+  ) {
+    polyfills = getPolyfills(targets, userPolyfills || defaultPolyfills, {
+      ignoreBrowserslistConfig,
+      configPath
+    })
+    plugins.push([require('./polyfillsPlugin'), { polyfills }])
+  } else {
+    polyfills = []
+  }
+
+  const envOptions = {
+    spec,
+    loose,
+    debug,
+    modules,
+    targets,
+    useBuiltIns,
+    ignoreBrowserslistConfig,
+    configPath,
+    include,
+    exclude: polyfills.concat(exclude || []),
+    shippedProposals,
+    forceAllTransforms
+  }
+
+  // cli-plugin-jest sets this to true because Jest runs without bundling
+  if (process.env.VUE_CLI_BABEL_TRANSPILE_MODULES) {
+    envOptions.modules = 'commonjs'
+    // necessary for dynamic import to work in tests
+    plugins.push(require('babel-plugin-dynamic-import-node'))
+  }
+
+  // pass options along to babel-preset-env
+  presets.push([require('@babel/preset-env'), envOptions])
+
+  // additional <= stage-3 plugins
+  // Babel 7 is removing stage presets altogether because people are using
+  // too many unstable proposals. Let's be conservative in the defaults here.
+  plugins.push(
+    require('@babel/plugin-syntax-dynamic-import'),
+    [require('@babel/plugin-proposal-decorators'), { legacy: decoratorsLegacy !== false }],
+    [require('@babel/plugin-proposal-class-properties'), { loose }],
+  )
+
+  // transform runtime, but only for helpers
+  plugins.push([require('@babel/plugin-transform-runtime'), {
+    regenerator: useBuiltIns !== 'usage',
+    corejs: useBuiltIns !== false ? false : 2,
+    helpers: useBuiltIns === 'usage',
+    useESModules: !process.env.VUE_CLI_BABEL_TRANSPILE_MODULES,
+    absoluteRuntime: path.dirname(require.resolve('@babel/runtime/package.json'))
+  }])
+
+  return {
+    presets,
+    plugins
+  }
+}