environment (#10)

* Revert "use eslint for both error check and code style"

This reverts commit 7996094.

* Revert "remove prettier: not mature enough for this project requirements"

This reverts commit b548a52.

* update prettier settings

* use Node.js v10

* upgrade packages

.eslintrc.js

@@ -1,5 +1,3 @@
-/* global module */
-
 module.exports = {
   env: {
     es6: true,
@@ -9,10 +7,17 @@ module.exports = {
     'eslint:recommended',
     'plugin:import/errors',
     'plugin:import/warnings',
-    './config/eslint/detect-errors.js',
-    './config/eslint/code-style.js',
+    'prettier',
   ],
   parserOptions: {
     sourceType: 'module',
   },
+  /*
+    User experience rules (bug prevention) should be added as "error".
+    Developer experience (code quality) rules should be added as "warn".
+    Code style rules shouldn't be added here, use prettier instead.
+  */
+  rules: {
+    'no-unused-vars': ['warn'],
+  },
 }

.nvmrc

@@ -1 +1 @@
-v8
+v10

.prettierrc.js

@@ -0,0 +1,7 @@
+module.exports = {
+  bracketSpacing: true,
+  printWidth: 100,
+  semi: false,
+  singleQuote: true,
+  trailingComma: 'all',
+}