chore: Upgrade eslint config

[G2Jose]

Description

Changes

Updated the following packages related to linting:

• eslint
• babel-eslint

Adds the following packages:

• prettier-eslint

Reformat files that do not comply with linting configuration.

• The main change is the later version of eslint applies bracket spacing rules to async functions too - Example here.

Rename .eslintrc -> .eslintrc.js so it can be automatically formatted too.

Motivation

• Versions of eslint, babel-eslint were outdated
• chore: Add typescript support #874 requires later versions of eslint & babel-eslint
• Using prettier + eslint separately sometimes causes weird conflicts, where eslint formats files one way, followed by prettier formatting it another way while running lint-staged. This was annoying in chore: Add typescript support #874. prettier-eslint was created exactly to solve this problem. See https://github.com/prettier/prettier-eslint

---

Question	Response
Version?	v1.4.1
Devices tested?	N/A
Bug fix?	no
New feature?	no
Includes tests?	no
All Tests pass?	yes
Related ticket?	N/A

[coveralls]

Coverage remained the same at 48.895% when pulling c314b18 on G2Jose:upgrade-eslint-config into 9af60b2 on gitpoint:master.

[chinesedfan]

Good enhancement. And I have few questions.

Rename .eslintrc -> .eslintrc.js so it can be automatically formatted too.

Is it depend on your IDE? I don't know why .eslintrc.js can work, but .eslintrc doesn't.

---

Edit: I found .eslintrc was deprecated, https://dev.to/ohbarye/eslintrc-without-file-extension-is-deprecated-3ngg. Is it the reason?

[chinesedfan]

Can we do some prettier/eslint configurations so that these changes will not be made? As well as the space after async and extra empty line between every let/const.

[chinesedfan]

Updates,

• Now prettier-eslint only supports eslint@4, Support eslint 5 prettier/prettier-eslint-cli#143
• We need upgrade eslint-config-airbnb to use eslint@5 (and remove eslint-config-airbnb-base?)
• Some rules are deprecated or needed to be updated, i.e.

-    'newline-after-var': ['error', 'always'],
-    'newline-before-return': 'error',
+    'padding-line-between-statements': [
+        2,
+        { 'blankLine': 'always', 'prev': '*', 'next': 'return' },
+        { 'blankLine': 'always', 'prev': ['var', 'let', 'const'], 'next': '*' },
+        { 'blankLine': 'any', 'prev': ['var', 'let', 'const'], 'next': ['var', 'let', 'const'] },
+    ],
     'newline-per-chained-call': 'off',
     'no-confusing-arrow': 'off',
     'no-mixed-operators': [
@@ -71,7 +75,14 @@ module.exports = {
         allowForLoopAfterthoughts: true,
       },
     ],
-    'space-before-function-paren': ['error', 'never'],
+    'space-before-function-paren': [
+      'error',
+      {
+        anonymous: 'never',
+        named: 'never',
+        asyncArrow: 'always'
+      }
+    ],

[chinesedfan]

prettier-eslint-cli@5 released today, with eslint@5.

@G2Jose Can you update this PR or would you mind me taking over it?

[chinesedfan]

Close in favor of #882. Still many thanks to @G2Jose.