introduce eslint

.eslintrc.js

@@ -0,0 +1,32 @@
+module.exports = {
+	root: true,
+	parser: '@typescript-eslint/parser',
+	plugins: [
+		'@typescript-eslint',
+	],
+	extends: [
+		'eslint:recommended',
+		'plugin:@typescript-eslint/recommended',
+	],
+	rules: {
+		'indent': ['error', 'tab', {
+			'SwitchCase': 1,
+			'flatTernaryExpressions': true,
+		}],
+		'eol-last': ['error', 'always'],
+		'semi': ['error', 'always'],
+		'quotes': ['error', 'single'],
+		'keyword-spacing': ['error', {
+			'before': true,
+			'after': true,
+		}],
+		'no-multi-spaces': ['error'],
+		'no-var': ['error'],
+		'prefer-arrow-callback': ['error'],
+		'no-throw-literal': ['error'],
+		'no-param-reassign': ['warn'],
+		'no-constant-condition': ['warn'],
+		'no-empty-pattern': ['warn'],
+		'@typescript-eslint/no-inferrable-types': ['off'],
+	},
+};