Add eslint settings for TypeScript (#1205)

* wip: Proposal of eslint setting of TypeScript.

* Add eslint settings for TypeScript

* Modify TypeScript lint target file

.eslintrc.js

@@ -0,0 +1,50 @@
+const javascriptSettings = {
+  files: ['*.js'],
+  extends: [
+    'standard',
+    'plugin:jest/recommended'
+  ],
+  rules: {
+    'no-else-return': ['error', { allowElseIf: false }],
+    'no-var': 'warn',
+    'one-var': 'off',
+    'space-before-function-paren': ['error', 'never'],
+    semi: ['error', 'always']
+  },
+}
+
+const typescriptSettings = {
+  files: ['*.ts'],
+  extends: ['standard-with-typescript'],
+  parserOptions: {
+    project: './tsconfig.json'
+  },
+  rules: {
+    'no-else-return': ['error', { allowElseIf: false }],
+    'no-var': 'warn',
+    'one-var': 'off',
+    'space-before-function-paren': ['error', 'never'],
+    semi: ['error', 'always'],
+    '@typescript-eslint/member-delimiter-style': [
+      'error',
+      {
+        multiline: {
+          delimiter: 'semi',
+          requireLast: true
+        },
+        singleline: {
+          delimiter: 'semi',
+          requireLast: false
+        }
+      }
+    ]
+  }
+}
+
+module.exports = {
+  plugins: ['jest'],
+  overrides: [
+    javascriptSettings,
+    typescriptSettings
+  ]
+}