Refactor ESLint configuration to enable better IDE integration

.eslintrc.js

@@ -1,5 +1,10 @@
 'use strict';
 
+const {
+  es5Paths,
+  esNextPaths,
+} = require('./scripts/shared/pathsByLanguageVersion');
+
 const OFF = 0;
 const ERROR = 2;
 
@@ -16,6 +21,15 @@ module.exports = {
     'react-internal',
   ],
 
+  parser: 'espree',
+  parserOptions: {
+    ecmaVersion: 2017,
+    sourceType: 'script',
+    ecmaFeatures: {
+      experimentalObjectRestSpread: true,
+    },
+  },
+
   // We're stricter than the default config, mostly. We'll override a few rules
   // and then enable some React specific ones.
   rules: {
@@ -44,6 +58,13 @@ module.exports = {
     'space-before-function-paren': OFF,
     'valid-typeof': [ERROR, {requireStringLiterals: true}],
 
+    // We apply these settings to files that should run on Node.
+    // They can't use JSX or ES6 modules, and must be in strict mode.
+    // They can, however, use other ES6 features.
+    // (Note these rules are overridden later for source files.)
+    'no-var': ERROR,
+    strict: ERROR,
+
     // React & JSX
     // Our transforms set this automatically
     'react/jsx-boolean-value': [ERROR, 'always'],
@@ -71,6 +92,33 @@ module.exports = {
   },
 
   overrides: [
+    {
+      // We apply these settings to files that we ship through npm.
+      // They must be ES5.
+      files: es5Paths,
+      parser: 'espree',
+      parserOptions: {
+        ecmaVersion: 5,
+        sourceType: 'script',
+      },
+      rules: {
+        'no-var': OFF,
+        strict: ERROR,
+      },
+    },
+    {
+      // We apply these settings to the source files that get compiled.
+      // They can use all features including JSX (but shouldn't use `var`).
+      files: esNextPaths,
+      parser: 'babel-eslint',
+      parserOptions: {
+        sourceType: 'module',
+      },
+      rules: {
+        'no-var': ERROR,
+        strict: OFF,
+      },
+    },
     {
       files: ['**/__tests__/*.js'],
       rules: {

packages/scheduler/npm/umd/scheduler-tracing.development.js

@@ -10,6 +10,7 @@
 'use strict';
 
 (function(global, factory) {
+  // eslint-disable-next-line no-unused-expressions
   typeof exports === 'object' && typeof module !== 'undefined'
     ? (module.exports = factory(require('react')))
     : typeof define === 'function' && define.amd // eslint-disable-line no-undef

packages/scheduler/npm/umd/scheduler-tracing.production.min.js

@@ -10,6 +10,7 @@
 'use strict';
 
 (function(global, factory) {
+  // eslint-disable-next-line no-unused-expressions
   typeof exports === 'object' && typeof module !== 'undefined'
     ? (module.exports = factory(require('react')))
     : typeof define === 'function' && define.amd // eslint-disable-line no-undef

packages/scheduler/npm/umd/scheduler-tracing.profiling.min.js

@@ -10,6 +10,7 @@
 'use strict';
 
 (function(global, factory) {
+  // eslint-disable-next-line no-unused-expressions
   typeof exports === 'object' && typeof module !== 'undefined'
     ? (module.exports = factory(require('react')))
     : typeof define === 'function' && define.amd // eslint-disable-line no-undef

packages/scheduler/npm/umd/scheduler.development.js

@@ -12,6 +12,7 @@
 'use strict';
 
 (function(global, factory) {
+  // eslint-disable-next-line no-unused-expressions
   typeof exports === 'object' && typeof module !== 'undefined'
     ? (module.exports = factory(require('react')))
     : typeof define === 'function' && define.amd // eslint-disable-line no-undef

packages/scheduler/npm/umd/scheduler.production.min.js

@@ -12,6 +12,7 @@
 'use strict';
 
 (function(global, factory) {
+  // eslint-disable-next-line no-unused-expressions
   typeof exports === 'object' && typeof module !== 'undefined'
     ? (module.exports = factory(require('react')))
     : typeof define === 'function' && define.amd // eslint-disable-line no-undef

packages/scheduler/npm/umd/scheduler.profiling.min.js

@@ -12,6 +12,7 @@
 'use strict';
 
 (function(global, factory) {
+  // eslint-disable-next-line no-unused-expressions
   typeof exports === 'object' && typeof module !== 'undefined'
     ? (module.exports = factory(require('react')))
     : typeof define === 'function' && define.amd // eslint-disable-line no-undef

scripts/eslint/index.js

@@ -10,7 +10,6 @@
 const minimatch = require('minimatch');
 const CLIEngine = require('eslint').CLIEngine;
 const listChangedFiles = require('../shared/listChangedFiles');
-const {es5Paths, esNextPaths} = require('../shared/pathsByLanguageVersion');
 
 const allPaths = ['**/*.js'];
 
@@ -65,25 +64,10 @@ function runESLint({onlyChanged}) {
   if (typeof onlyChanged !== 'boolean') {
     throw new Error('Pass options.onlyChanged as a boolean.');
   }
-  let errorCount = 0;
-  let warningCount = 0;
-  let output = '';
-  [
-    runESLintOnFilesWithOptions(allPaths, onlyChanged, {
-      configFile: `${__dirname}/eslintrc.default.js`,
-      ignorePattern: [...es5Paths, ...esNextPaths],
-    }),
-    runESLintOnFilesWithOptions(esNextPaths, onlyChanged, {
-      configFile: `${__dirname}/eslintrc.esnext.js`,
-    }),
-    runESLintOnFilesWithOptions(es5Paths, onlyChanged, {
-      configFile: `${__dirname}/eslintrc.es5.js`,
-    }),
-  ].forEach(result => {
-    errorCount += result.errorCount;
-    warningCount += result.warningCount;
-    output += result.output;
-  });
+  const {errorCount, warningCount, output} = runESLintOnFilesWithOptions(
+    allPaths,
+    onlyChanged
+  );
   console.log(output);
   return errorCount === 0 && warningCount === 0;
 }