refactor(cli): default to .js for eslintrc and postcssrc

close #994

packages/@vue/cli-plugin-eslint/generator.js

@@ -73,7 +73,7 @@ module.exports = (api, { config, lintOn = [] }) => {
       }
     }
     api.render(files => {
-      files['tests/unit/.eslintrc'] = JSON.stringify(config, null, 2)
+      files['tests/unit/.eslintrc.js'] = api.genJSConfig(config)
     })
   } else if (api.hasPlugin('unit-jest')) {
     const config = {
@@ -85,7 +85,7 @@ module.exports = (api, { config, lintOn = [] }) => {
       }
     }
     api.render(files => {
-      files['tests/unit/.eslintrc'] = JSON.stringify(config, null, 2)
+      files['tests/unit/.eslintrc.js'] = api.genJSConfig(config)
     })
   }
 

packages/@vue/cli-plugin-typescript/generator/index.js

@@ -112,7 +112,7 @@ module.exports = (api, {
   // delete all js files that have a ts file of the same name
   // and simply rename other js files to ts
   const jsRE = /\.js$/
-  const excludeRE = /^tests\/e2e\/|\.config\.js$/
+  const excludeRE = /^tests\/e2e\/|(\.config|rc)\.js$/
   const convertLintFlags = require('../lib/convertLintFlags')
   api.postProcessFiles(files => {
     for (const file in files) {

packages/@vue/cli-plugin-unit-jest/__tests__/jestGenerator.spec.js

@@ -18,7 +18,7 @@ test('base', async () => {
   expect(pkg.scripts.test).toBeTruthy()
   expect(pkg.devDependencies).toHaveProperty('@vue/test-utils')
   expect(pkg.devDependencies).toHaveProperty('babel-jest')
-  expect(files['tests/unit/.eslintrc']).toMatch('"jest": true')
+  expect(files['tests/unit/.eslintrc.js']).toMatch('jest: true')
 
   const spec = files['tests/unit/HelloWorld.spec.js']
   expect(spec).toMatch(`expect(wrapper.text()).toMatch(msg)`)

packages/@vue/cli-plugin-unit-jest/generator/index.js

@@ -65,12 +65,12 @@ module.exports = api => {
 
   if (api.hasPlugin('eslint')) {
     api.render(files => {
-      files['tests/unit/.eslintrc'] = JSON.stringify({
+      files['tests/unit/.eslintrc.js'] = api.genJSConfig({
         env: { jest: true },
         rules: {
           'import/no-extraneous-dependencies': 'off'
         }
-      }, null, 2)
+      })
     })
   }
 }

packages/@vue/cli-plugin-unit-mocha/__tests__/mochaGenerator.spec.js

@@ -17,7 +17,7 @@ test('base', async () => {
 
   expect(pkg.scripts.test).toBeTruthy()
   expect(pkg.devDependencies).toHaveProperty('@vue/test-utils')
-  expect(files['tests/unit/.eslintrc']).toMatch('"mocha": true')
+  expect(files['tests/unit/.eslintrc.js']).toMatch('mocha: true')
 
   const spec = files['tests/unit/HelloWorld.spec.js']
   expect(spec).toMatch(`import { expect } from 'chai'`)

packages/@vue/cli-plugin-unit-mocha/generator/index.js

@@ -15,12 +15,12 @@ module.exports = api => {
 
   if (api.hasPlugin('eslint')) {
     api.render(files => {
-      files['tests/unit/.eslintrc'] = JSON.stringify({
+      files['tests/unit/.eslintrc.js'] = api.genJSConfig({
         env: { mocha: true },
         rules: {
           'import/no-extraneous-dependencies': 'off'
         }
-      }, null, 2)
+      })
     })
   }
 }

packages/@vue/cli/__tests__/Generator.spec.js

@@ -4,6 +4,7 @@ const fs = require('fs')
 const path = require('path')
 const Generator = require('../lib/Generator')
 const { logs } = require('@vue/cli-shared-utils')
+const stringifyJS = require('javascript-stringify')
 
 // prepare template fixtures
 const mkdirp = require('mkdirp')
@@ -327,7 +328,7 @@ test('api: resolve', () => {
 test('extract config files', async () => {
   const configs = {
     vue: {
-      lintOnSave: true
+      lintOnSave: false
     },
     babel: {
       presets: ['@vue/app']
@@ -357,9 +358,10 @@ test('extract config files', async () => {
   })
 
   const json = v => JSON.stringify(v, null, 2)
-  expect(fs.readFileSync('/vue.config.js', 'utf-8')).toMatch('module.exports = {\n  lintOnSave: true\n}')
+  const js = v => `module.exports = ${stringifyJS(v, null, 2)}`
+  expect(fs.readFileSync('/vue.config.js', 'utf-8')).toMatch(js(configs.vue))
   expect(fs.readFileSync('/.babelrc', 'utf-8')).toMatch(json(configs.babel))
-  expect(fs.readFileSync('/.postcssrc', 'utf-8')).toMatch(json(configs.postcss))
-  expect(fs.readFileSync('/.eslintrc', 'utf-8')).toMatch(json(configs.eslintConfig))
-  expect(fs.readFileSync('/jest.config.js', 'utf-8')).toMatch(`module.exports = {\n  foo: 'bar'\n}`)
+  expect(fs.readFileSync('/.postcssrc.js', 'utf-8')).toMatch(js(configs.postcss))
+  expect(fs.readFileSync('/.eslintrc.js', 'utf-8')).toMatch(js(configs.eslintConfig))
+  expect(fs.readFileSync('/jest.config.js', 'utf-8')).toMatch(js(configs.jest))
 })

packages/@vue/cli/__tests__/invoke.spec.js

@@ -4,6 +4,8 @@ jest.mock('inquirer')
 const invoke = require('../lib/invoke')
 const { expectPrompts } = require('inquirer')
 const create = require('@vue/cli-test-utils/createTestProject')
+const stringifyJS = require('javascript-stringify')
+const toJS = v => `module.exports = ${stringifyJS(v, null, 2)}`
 
 async function createAndInstall (name) {
   const project = await create(name, {
@@ -26,11 +28,11 @@ async function assertUpdates (project) {
     'pre-commit': 'lint-staged'
   })
 
-  const eslintrc = JSON.parse(await project.read('.eslintrc'))
-  expect(eslintrc).toEqual({
+  const eslintrc = await project.read('.eslintrc.js')
+  expect(eslintrc).toEqual(toJS({
     root: true,
     extends: ['plugin:vue/essential', '@vue/airbnb']
-  })
+  }))
 
   const lintedMain = await project.read('src/main.js')
   expect(lintedMain).toMatch(';') // should've been linted in post-generate hook
@@ -78,11 +80,11 @@ test('invoke with existing files', async () => {
   // mock existing vue.config.js
   await project.write('vue.config.js', `module.exports = { lintOnSave: true }`)
 
-  const eslintrc = JSON.parse(await project.read('.eslintrc'))
-  expect(eslintrc).toEqual({
+  const eslintrc = await project.read('.eslintrc.js')
+  expect(eslintrc).toEqual(toJS({
     root: true,
     extends: ['plugin:vue/essential', 'eslint:recommended']
-  })
+  }))
 
   await project.run(`${require.resolve('../bin/vue')} invoke eslint --config airbnb --lintOn commit`)
 
@@ -104,13 +106,13 @@ test('invoke with existing files (yaml)', async () => {
   pkg.devDependencies['@vue/cli-plugin-eslint'] = '*'
   await project.write('package.json', JSON.stringify(pkg, null, 2))
 
-  const eslintrc = JSON.parse(await project.read('.eslintrc'))
-  expect(eslintrc).toEqual({
+  const eslintrc = await project.read('.eslintrc.js')
+  expect(eslintrc).toEqual(toJS({
     root: true,
     extends: ['plugin:vue/essential', 'eslint:recommended']
-  })
+  }))
 
-  await project.rm(`.eslintrc`)
+  await project.rm(`.eslintrc.js`)
   await project.write(`.eslintrc.yml`, `
 root: true
 extends:

packages/@vue/cli/lib/GeneratorAPI.js

@@ -7,6 +7,7 @@ const resolve = require('resolve')
 const isBinary = require('isbinaryfile')
 const yaml = require('yaml-front-matter')
 const mergeDeps = require('./util/mergeDeps')
+const stringifyJS = require('javascript-stringify')
 const { getPluginLink, toShortPluginId } = require('@vue/cli-shared-utils')
 
 const isString = val => typeof val === 'string'
@@ -191,6 +192,13 @@ class GeneratorAPI {
   exitLog (msg, type = 'log') {
     this.generator.exitLogs.push({ id: this.id, msg, type })
   }
+
+  /**
+   * convenience method for generating a js config file from json
+   */
+  genJSConfig (value) {
+    return `module.exports = ${stringifyJS(value, null, 2)}`
+  }
 }
 
 function extractCallDir () {

packages/@vue/cli/lib/util/configTransforms.js

@@ -35,11 +35,20 @@ function makeJSONTransform (filename) {
   }
 }
 
-function makeMutliExtensionJSONTransform (filename) {
+function makeMutliExtensionJSONTransform (filename, preferJS) {
   return function transformToMultiExtensions (value, checkExisting, context) {
-    if (!checkExisting) {
-      return makeJSONTransform(filename)(value, checkExisting, context)
+    function defaultTransform () {
+      if (preferJS) {
+        return makeJSTransform(`${filename}.js`)(value, false, context)
+      } else {
+        return makeJSONTransform(filename)(value, false, context)
+      }
     }
+
+    if (!checkExisting) {
+      return defaultTransform()
+    }
+
     const absolutePath = path.resolve(context, filename)
     if (fs.existsSync(absolutePath)) {
       return makeJSONTransform(filename)(value, checkExisting, context)
@@ -52,7 +61,7 @@ function makeMutliExtensionJSONTransform (filename) {
     } else if (fs.existsSync(`${absolutePath}.yml`)) {
       return transformYAML(value, `${filename}.yml`, fs.readFileSync(`${absolutePath}.yml`, 'utf-8'))
     } else {
-      return makeJSONTransform(filename)(value, false, context)
+      return defaultTransform()
     }
   }
 }
@@ -69,7 +78,7 @@ function transformYAML (value, filename, source) {
 module.exports = {
   vue: makeJSTransform('vue.config.js'),
   babel: makeJSONTransform('.babelrc'),
-  postcss: makeMutliExtensionJSONTransform('.postcssrc'),
-  eslintConfig: makeMutliExtensionJSONTransform('.eslintrc'),
+  postcss: makeMutliExtensionJSONTransform('.postcssrc', true),
+  eslintConfig: makeMutliExtensionJSONTransform('.eslintrc', true),
   jest: makeJSTransform('jest.config.js')
 }