Use eslint

.eslintignore

@@ -0,0 +1,3 @@
+dist/
+lib/
+node_modules/

.eslintrc.json

@@ -0,0 +1,56 @@
+{
+    "plugins": ["jest", "@typescript-eslint"],
+    "extends": ["plugin:github/recommended"],
+    "parser": "@typescript-eslint/parser",
+    "parserOptions": {
+      "ecmaVersion": 9,
+      "sourceType": "module",
+      "project": "./tsconfig.json"
+    },
+    "rules": {
+      "eslint-comments/no-use": "off",
+      "import/no-namespace": "off",
+      "i18n-text/no-en": "off",
+      "no-unused-vars": "off",
+      "no-shadow": "off",
+      "sort-imports": "off",
+      "@typescript-eslint/no-unused-vars": ["error", { "argsIgnorePattern": "^_" }],
+      "@typescript-eslint/explicit-member-accessibility": ["error", {"accessibility": "no-public"}],
+      "@typescript-eslint/no-require-imports": "error",
+      "@typescript-eslint/array-type": "error",
+      "@typescript-eslint/await-thenable": "error",
+      "camelcase": "off",
+      "@typescript-eslint/explicit-function-return-type": ["error", {"allowExpressions": true}],
+      "@typescript-eslint/func-call-spacing": ["error", "never"],
+      "@typescript-eslint/no-array-constructor": "error",
+      "@typescript-eslint/no-empty-interface": "error",
+      "@typescript-eslint/no-explicit-any": "error",
+      "@typescript-eslint/no-extraneous-class": "error",
+      "@typescript-eslint/no-for-in-array": "error",
+      "@typescript-eslint/no-inferrable-types": "error",
+      "@typescript-eslint/no-misused-new": "error",
+      "@typescript-eslint/no-namespace": "error", 
+      "@typescript-eslint/no-non-null-assertion": "off",
+      "@typescript-eslint/no-shadow": "error",
+      "@typescript-eslint/no-unnecessary-qualifier": "error",
+      "@typescript-eslint/no-unnecessary-type-assertion": "error",
+      "@typescript-eslint/no-useless-constructor": "error",
+      "@typescript-eslint/no-var-requires": "error",
+      "@typescript-eslint/prefer-for-of": "warn",
+      "@typescript-eslint/prefer-function-type": "warn",
+      "@typescript-eslint/prefer-includes": "error",
+      "@typescript-eslint/prefer-string-starts-ends-with": "error",
+      "@typescript-eslint/promise-function-async": "error",
+      "@typescript-eslint/require-array-sort-compare": ["error", {"ignoreStringArrays":  true}],
+      "@typescript-eslint/restrict-plus-operands": "error",
+      "semi": "off",
+      "@typescript-eslint/semi": ["error", "never"],
+      "@typescript-eslint/type-annotation-spacing": "error",
+      "@typescript-eslint/unbound-method": "error"
+    },
+    "env": {
+      "node": true,
+      "es6": true,
+      "jest/globals": true
+    }
+  }