Add eslint

.eslintrc.js

@@ -0,0 +1,19 @@
+module.exports = {
+  extends: ['eslint:recommended', 'plugin:prettier/recommended'],
+  plugins: ['@typescript-eslint'],
+  env: {
+    node: true,
+    es6: true,
+  },
+  parser: '@typescript-eslint/parser',
+  parserOptions: {
+    sourceType: 'module',
+    project: './tsconfig.json',
+  },
+  rules: {
+    camelcase: 'off',
+    '@typescript-eslint/camelcase': 'error',
+    'no-unused-vars': 'off',
+    'no-console': 'off',
+  },
+};

package.json

@@ -4,7 +4,9 @@
   "scripts": {
     "typecheck": "tsc --noEmit",
     "build": "node fuse",
-    "build:watch": "node fuse --variant watch"
+    "build:watch": "node fuse --variant watch",
+    "lint": "eslint --cache --ext .ts src",
+    "lint:fix": "yarn lint --fix"
   },
   "dependencies": {
     "actions-toolkit": "^1.4.1",
@@ -14,7 +16,12 @@
   "devDependencies": {
     "@types/lodash": "^4.14.120",
     "@types/node": "^10.12.24",
+    "@typescript-eslint/eslint-plugin": "^1.3.0",
+    "eslint": "^5.14.0",
+    "eslint-config-prettier": "^4.0.0",
+    "eslint-plugin-prettier": "^3.0.1",
     "fuse-box": "^3.7.0",
+    "prettier": "^1.16.4",
     "tslib": "^1.9.3",
     "typescript": "^3.3.3",
     "yargs": "^12.0.5"