Merge pull request #22 from hexojs/es6-rule

feat: prefer ES6 syntax

Author: curbengh

eslint.js

@@ -85,6 +85,7 @@ module.exports = {
     'no-array-constructor': 'error',
     'no-extra-label': 'error',
     'no-multiple-empty-lines': 'error',
+    'no-multi-assign': 'error',
     'no-nested-ternary': 'error',
     'no-new-object': 'error',
     'no-trailing-spaces': 'error',
@@ -113,13 +114,18 @@ module.exports = {
     'template-tag-spacing': 'error',
     'unicode-bom': 'error',
     // ECMAScript 6
+    'arrow-parens': ['error', 'as-needed'],
     'arrow-spacing': 'error',
     'generator-star-spacing': ['error', 'after'],
     'no-confusing-arrow': ['error', { allowParens: true }],
+    'no-const-assign': 'error',
     'no-duplicate-imports': 'error',
     'no-useless-computed-key': 'error',
     'no-useless-constructor': 'error',
     'no-useless-rename': 'error',
+    'no-var': 'error',
+    'prefer-arrow-callback': 'error',
+    'prefer-const': ['error', { ignoreReadBeforeAssign: true }],
     'rest-spread-spacing': 'error',
     'template-curly-spacing': 'error',
     'yield-star-spacing': 'error',