add eslint

.eslintrc.js

@@ -0,0 +1,14 @@
+module.exports = {
+  parser: '@typescript-eslint/parser', // Specifies the ESLint parser
+  extends: [
+    'plugin:@typescript-eslint/recommended', // Uses the recommended rules from the @typescript-eslint/eslint-plugin
+  ],
+  parserOptions: {
+    ecmaVersion: 2018, // Allows for the parsing of modern ECMAScript features
+    sourceType: 'module', // Allows for the use of imports
+  },
+  rules: {
+    // Place to specify ESLint rules. Can be used to overwrite rules specified from the extended configs
+    // e.g. "@typescript-eslint/explicit-function-return-type": "off",
+  },
+};

.gitignore

@@ -2,3 +2,4 @@ dist
 node_modules
 .vscode
 built
+.eslintcache

package.json

@@ -17,9 +17,12 @@
   "devDependencies": {
     "@types/jest": "23.1.4",
     "@types/node": "10.5.2",
+    "@typescript-eslint/eslint-plugin": "2.2.0",
+    "@typescript-eslint/parser": "2.2.0",
     "babel-core": "^6.26.3",
     "babel-jest": "^23.2.0",
     "copy-webpack-plugin": "4.5.1",
+    "eslint": "6.3.0",
     "husky": "1.1.2",
     "jest": "23.3.0",
     "prettier": "1.18.2",