Initial commit

.gitignore

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+node_modules

LICENSE

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+The MIT License (MIT)
+
+Copyright (c) 2016 Kensho Technologies, Inc
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

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+# eslint-config-kensho
+
+This [eslint config](http://eslint.org/docs/developer-guide/shareable-configs) extends [Airbnb's config](https://github.com/airbnb/javascript/tree/master/packages/eslint-config-airbnb) (based on their [style guide](https://github.com/airbnb/javascript)).
+
+Since the upstream config is well-maintained and justified, we try to stick as close to it as possible. All divergences are [annotated](index.js), and tend towards increased ES2016+ support and compatibility with our infrastructure rather than stylistic preferences.
+
+## Usage
+
+To add JS linting to a project, first install eslint and this config as development dependencies:
+
+```sh
+$ npm i -D eslint eslint-config-kensho
+```
+
+Add a [**.eslintrc.json**](http://eslint.org/docs/user-guide/configuring) which extends the config:
+
+```json
+{
+  "extends": "kensho"
+}
+```
+
+Add a script in **package.json** to [run the linter](http://eslint.org/docs/user-guide/command-line-interface). Example:
+
+```json
+{
+  "scripts": {
+    "lint": "eslint src"
+  }
+}
+```
+
+## Caveat
+
+The eslint-plugin-X dependencies specified in [package.json](package.json) should actually be peer dependencies (see eslint/eslint#2518), and installed alongside eslint and this config. In practice, this is quite tedious, so we have instead specified them as dependencies and rely on npm@3's flattening to install them alongside the linter.
+
+Note that this approach is technically incorrect, and if any plugin cannot be flattened this way (e.g. due to a conflicting version somewhere else in your dependency tree), **this config will break**. Since our projects use only this config, we feel that practicality outweighs absolute correctness in this case.

index.js

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+module.exports = {
+  extends: 'airbnb',
+  plugins: ['babel'],
+  parser: 'babel-eslint',
+  env: {
+    // allow browser globals
+    browser: true,
+  },
+  rules: {
+    // allow parens around arrow functions only when necessary (0 or >=2 args)
+    'arrow-parens': [2, 'as-needed'],
+
+    // require trailing commas in all contexts except function calls
+    'comma-dangle': [2, 'always-multiline'],
+
+    // allow require() calls
+    'global-require': 0,
+
+    // ensure that default, named, and namespaced imports have been exported by the target file
+    'import/default': 2,
+    'import/named': 2,
+    'import/namespace': 2,
+
+    // require all module imports to be declared as (dev-)dependencies in package.json
+    'import/no-extraneous-dependencies': [2, {devDependencies: true}],
+
+    // require import groups to be ordered by specificity and separated by linebreaks
+    'import/order': [2, {'newlines-between': 'always'}],
+
+    // allow files with a single named export (to allow in-progress util files)
+    'import/prefer-default-export': 0,
+
+    // allow non-ID-linked <label>s to accomodate those containing linked <input>s
+    'jsx-a11y/label-has-for': 0,
+
+    // require single quotes in JSX
+    'jsx-quotes': [2, 'prefer-single'],
+
+    // require multi-line operators to occur at the start of the line, except && and ||
+    'operator-linebreak': [2, 'before', {overrides: {'&&': 'after', '||': 'after'}}],
+
+    // allow supposedly-confusing arrows
+    'no-confusing-arrow': 0,
+
+    // do not allow more than one empty line anywhere
+    'no-multiple-empty-lines': [2, {max: 1, maxEOF: 1}],
+
+    // disallow confusing global browser variables
+    'no-restricted-globals': ['error', 'event', 'find'],
+
+    // allow variable shadowing, just for convenience
+    // TODO: enable?
+    'no-shadow': 0,
+
+    // allow dangling underscores in variable names (for "private" class methods)
+    'no-underscore-dangle': 0,
+
+    // disallow spaces in between curly braces
+    'babel/object-curly-spacing': [2, 'never'],
+    'object-curly-spacing': 0,
+
+    // disallow .jsx files for consistency
+    'react/jsx-filename-extension': 0,
+
+    // do not require a React import to use JSX (it's included automatically in our Babel preset)
+    'react/react-in-jsx-scope': 0,
+
+    // disallow semicolons
+    'semi': [2, 'never'],
+
+    // don't enforce JSX indentation, due to bugginess of the linter implementation :(
+    // TODO: https://github.com/yannickcr/eslint-plugin-react/issues/540
+    'react/jsx-indent': 0,
+    'react/jsx-indent-props': 0,
+    'react/jsx-closing-bracket-location': 0,
+
+    // TODO: enable when less buggy
+    'react/no-unused-prop-types': 0,
+
+    // allow event listeners on static elements (e.g. onClick on divs)
+    'jsx-a11y/no-static-element-interactions': 0,
+  },
+  settings: {
+    // do not attempt to parse npm modules or non-JS files for exports
+    'import/ignore': [
+      'node_modules',
+      '\.(png|svg|jpg|css|pdf)$'
+    ],
+    'import/extensions': [
+      '.js'
+    ],
+  },
+}

package.json

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+{
+  "name": "eslint-config-kensho",
+  "version": "0.0.0",
+  "description": "Standard Kensho config to lint JS files.",
+  "main": "index.js",
+  "author": "Billy Janitsch <billyjanitsch@gmail.com> (http://billyjanitsch.com)",
+  "license": "MIT",
+  "repository": "kensho/eslint-config-kensho",
+  "scripts": {
+    "test": "ava"
+  },
+  "files": [
+    "index.js"
+  ],
+  "dependencies": {
+    "babel-eslint": "^7.1.1",
+    "eslint-config-airbnb": "^13.0.0",
+    "eslint-plugin-babel": "^4.0.0",
+    "eslint-plugin-import": "^2.2.0",
+    "eslint-plugin-jsx-a11y": "^2.2.3",
+    "eslint-plugin-react": "^6.7.1"
+  },
+  "devDependencies": {
+    "ava": "^0.17.0",
+    "eslint": "^3.10.2"
+  }
+}

test/.eslintrc.js

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+module.exports = require('..')

test/fixtures/commas.js

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+export const objGood = {
+  a: 1,
+  b: 2,
+}
+
+export const objBad = {
+  a: 1,
+  b: 2 // missing comma
+}
+
+export const arrGood = [
+  1,
+  2,
+]
+
+export const arrBad = [
+  1,
+  2 // missing comma
+]

test/fixtures/exports.js

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+export const foo = 5
+// does not export bar
+export default 6

test/fixtures/import.js

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+import x, {foo, bar} from './exports' // bar is not exported
+import baz from './nonexistent' // file does not exist
+
+export {foo, bar, baz, x}

test/fixtures/linebreaks.js

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+export const a = 1
+
+
+export const b = 1 // extra newline

test/fixtures/operator.js

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+export const a = process.env.NODE_ENV === 'development' ? // ? ending line
+  10 : // : ending line
+  20
+
+export const b = process.env.NODE_ENV === 'development'
+  && 10 // && beginning line
+
+export const c = process.env.NODE_ENV === 'development'
+  || 10 // || beginning line

test/fixtures/prop-types.js

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+const MyComponent = props =>
+  <div>{props.myProp}</div> // missing prop type
+
+export default MyComponent

test/fixtures/variables.js

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+export const globalA = find([]) // confusing global var
+export const globalB = implicitGlobal() // implicit global var
+
+const unusedA = 1 // unused
+
+export const functionA = (a) => a // unnecessary parens
+
+export const functionB = a => { // unnecessary block
+  return a
+}

test/index.js

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+import test from 'ava'
+import {CLIEngine} from 'eslint'
+
+const cli = new CLIEngine()
+const formatter = cli.getFormatter()
+
+const invalid = async (t, input, count = 1) => {
+  const result = await cli.executeOnFiles([`${__dirname}/fixtures/${input}.js`])
+  t.is(result.errorCount, count, formatter(result.results))
+  t.is(result.warningCount, 0, formatter(result.results))
+}
+
+invalid.title = provided => `correctly lints issues with ${provided}`
+
+test('operator placement', invalid, 'operator', 4)
+test('line breaks', invalid, 'linebreaks')
+test('imports', invalid, 'import', 3)
+test('missing propTypes', invalid, 'prop-types')
+test('variables', invalid, 'variables', 5)
+test('commas', invalid, 'commas', 2)