add npm-run-all --parallel

.babelrc

@@ -7,7 +7,6 @@
           "node": "10"
         }
       }
-    ],
-    "@babel/preset-typescript"
+    ]
   ]
 }

.eslintrc

@@ -1,31 +1,25 @@
 {
+  "parser": "@typescript-eslint/parser",
   "parserOptions": {
     "ecmaVersion": 2019,
     "sourceType": "module",
     "ecmaFeatures": {
       "jsx": true
-    }
+    },
+    "project": "./tsconfig.json"
   },
-  "extends": ["eslint:recommended", "eslint-config-prettier"],
+  "plugins": ["@typescript-eslint/eslint-plugin"],
+  "extends": [
+    "eslint:recommended",
+    "plugin:@typescript-eslint/eslint-recommended",
+    "plugin:@typescript-eslint/recommended",
+    "eslint-config-prettier",
+    "eslint-config-prettier/@typescript-eslint"
+  ],
   "rules": {
     "strict": ["error", "never"]
   },
   "env": {
     "browser": true
-  },
-  "overrides": [
-    {
-      "files": "**/*.+(ts|tsx)",
-      "parser": "@typescript-eslint/parser",
-      "parserOptions": {
-        "project": "./tsconfig.json"
-      },
-      "plugins": ["@typescript-eslint/eslint-plugin"],
-      "extends": [
-        "plugin:@typescript-eslint/eslint-recommended",
-        "plugin:@typescript-eslint/recommended",
-        "eslint-config-prettier/@typescript-eslint"
-      ]
-    }
-  ]
+  }
 }

.huskyrc

@@ -1,5 +1,5 @@
 {
   "hooks": {
-    "pre-commit": "npm run validate"
+    "pre-commit": "npm run check-types && lint-staged"
   }
 }

.lintstagedrc

@@ -0,0 +1,9 @@
+{
+  "*.js": [
+    "eslint"
+  ],
+  "*.+(js|json|ts)": [
+    "prettier --write",
+    "git add"
+  ]
+}

package.json

@@ -4,25 +4,26 @@
   "author": "Kent C. Dodds (http://kentcdodds.com/)",
   "license": "GPLv3",
   "scripts": {
-    "build": "babel src --extensions .js,.ts,.tsx --out-dir dist",
+    "build": "babel src --out-dir dist",
     "lint": "eslint --ignore-path .gitignore --ext .js,.ts,.tsx .",
     "check-types": "tsc",
-    "prettier": "prettier --ignore-path .gitignore \"**/*.+(js|json|ts|tsx)\"",
+    "prettier": "prettier --ignore-path .gitignore --write \"**/*.+(js|json)\"",
     "format": "npm run prettier -- --write",
     "check-format": "npm run prettier -- --list-different",
-    "validate": "npm run check-types && npm run check-format && npm run lint && npm run build"
+    "validate": "npm-run-all --parallel check-types check-format lint build"
   },
   "devDependencies": {
-    "@babel/cli": "^7.7.0",
-    "@babel/core": "^7.7.2",
-    "@babel/preset-env": "^7.7.1",
-    "@babel/preset-typescript": "^7.7.2",
-    "@typescript-eslint/eslint-plugin": "^2.7.0",
-    "@typescript-eslint/parser": "^2.7.0",
-    "eslint": "^6.6.0",
-    "eslint-config-prettier": "^6.5.0",
-    "husky": "^3.0.9",
-    "prettier": "^1.19.1",
-    "typescript": "^3.7.2"
+    "@babel/cli": "^7.5.5",
+    "@babel/core": "^7.5.5",
+    "@babel/preset-env": "^7.5.5",
+    "@typescript-eslint/eslint-plugin": "^2.0.0",
+    "@typescript-eslint/parser": "^2.0.0",
+    "eslint": "^6.1.0",
+    "eslint-config-prettier": "^6.0.0",
+    "husky": "^3.0.2",
+    "lint-staged": "^9.2.1",
+    "npm-run-all": "^4.1.5",
+    "prettier": "^1.18.2",
+    "typescript": "^3.5.3"
   }
 }

tsconfig.json

@@ -1,5 +1,8 @@
 {
   "compilerOptions": {
+    // because we're compiling with Babel instead of TypeScript
+    // and we're only using TypeScript for type checking, we'll set "noEmit"
+    // to true so running type checking doesn't generate any files.
     "noEmit": true,
     "baseUrl": "./src"
   }