add typescript

.babelrc

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

package-lock.json

@@ -110,6 +110,20 @@
         "@babel/types": "^7.7.0"
       }
     },
+    "@babel/helper-create-class-features-plugin": {
+      "version": "7.7.0",
+      "resolved": "https://registry.npmjs.org/@babel/helper-create-class-features-plugin/-/helper-create-class-features-plugin-7.7.0.tgz",
+      "integrity": "sha512-MZiB5qvTWoyiFOgootmRSDV1udjIqJW/8lmxgzKq6oDqxdmHUjeP2ZUOmgHdYjmUVNABqRrHjYAYRvj8Eox/UA==",
+      "dev": true,
+      "requires": {
+        "@babel/helper-function-name": "^7.7.0",
+        "@babel/helper-member-expression-to-functions": "^7.7.0",
+        "@babel/helper-optimise-call-expression": "^7.7.0",
+        "@babel/helper-plugin-utils": "^7.0.0",
+        "@babel/helper-replace-supers": "^7.7.0",
+        "@babel/helper-split-export-declaration": "^7.7.0"
+      }
+    },
     "@babel/helper-create-regexp-features-plugin": {
       "version": "7.7.2",
       "resolved": "https://registry.npmjs.org/@babel/helper-create-regexp-features-plugin/-/helper-create-regexp-features-plugin-7.7.2.tgz",
@@ -425,6 +439,15 @@
         "@babel/helper-plugin-utils": "^7.0.0"
       }
     },
+    "@babel/plugin-syntax-typescript": {
+      "version": "7.3.3",
+      "resolved": "https://registry.npmjs.org/@babel/plugin-syntax-typescript/-/plugin-syntax-typescript-7.3.3.tgz",
+      "integrity": "sha512-dGwbSMA1YhVS8+31CnPR7LB4pcbrzcV99wQzby4uAfrkZPYZlQ7ImwdpzLqi6Z6IL02b8IAL379CaMwo0x5Lag==",
+      "dev": true,
+      "requires": {
+        "@babel/helper-plugin-utils": "^7.0.0"
+      }
+    },
     "@babel/plugin-transform-arrow-functions": {
       "version": "7.2.0",
       "resolved": "https://registry.npmjs.org/@babel/plugin-transform-arrow-functions/-/plugin-transform-arrow-functions-7.2.0.tgz",
@@ -721,6 +744,17 @@
         "@babel/helper-plugin-utils": "^7.0.0"
       }
     },
+    "@babel/plugin-transform-typescript": {
+      "version": "7.7.2",
+      "resolved": "https://registry.npmjs.org/@babel/plugin-transform-typescript/-/plugin-transform-typescript-7.7.2.tgz",
+      "integrity": "sha512-UWhDaJRqdPUtdK1s0sKYdoRuqK0NepjZto2UZltvuCgMoMZmdjhgz5hcRokie/3aYEaSz3xvusyoayVaq4PjRg==",
+      "dev": true,
+      "requires": {
+        "@babel/helper-create-class-features-plugin": "^7.7.0",
+        "@babel/helper-plugin-utils": "^7.0.0",
+        "@babel/plugin-syntax-typescript": "^7.2.0"
+      }
+    },
     "@babel/plugin-transform-unicode-regex": {
       "version": "7.7.0",
       "resolved": "https://registry.npmjs.org/@babel/plugin-transform-unicode-regex/-/plugin-transform-unicode-regex-7.7.0.tgz",
@@ -790,6 +824,16 @@
         "semver": "^5.5.0"
       }
     },
+    "@babel/preset-typescript": {
+      "version": "7.7.2",
+      "resolved": "https://registry.npmjs.org/@babel/preset-typescript/-/preset-typescript-7.7.2.tgz",
+      "integrity": "sha512-1B4HthAelaLGfNRyrWqJtBEjXX1ulThCrLQ5B2VOtEAznWFIFXFJahgXImqppy66lx/Oh+cOSCQdJzZqh2Jh5g==",
+      "dev": true,
+      "requires": {
+        "@babel/helper-plugin-utils": "^7.0.0",
+        "@babel/plugin-transform-typescript": "^7.7.2"
+      }
+    },
     "@babel/template": {
       "version": "7.7.0",
       "resolved": "https://registry.npmjs.org/@babel/template/-/template-7.7.0.tgz",
@@ -3894,6 +3938,12 @@
       "integrity": "sha512-DWkS49EQKVX//Tbupb9TFa19c7+MK1XmzkrZUR8TAktmE/DizXoaoJV6TZ/tSIPXipqNiRI6CyAe7x69Jb6RSw==",
       "dev": true
     },
+    "typescript": {
+      "version": "3.7.2",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-3.7.2.tgz",
+      "integrity": "sha512-ml7V7JfiN2Xwvcer+XAf2csGO1bPBdRbFCkYBczNZggrBZ9c7G3riSUeJmqEU5uOtXNPMhE3n+R4FA/3YOAWOQ==",
+      "dev": true
+    },
     "unicode-canonical-property-names-ecmascript": {
       "version": "1.0.4",
       "resolved": "https://registry.npmjs.org/unicode-canonical-property-names-ecmascript/-/unicode-canonical-property-names-ecmascript-1.0.4.tgz",

package.json

@@ -4,19 +4,22 @@
   "author": "Kent C. Dodds (http://kentcdodds.com/)",
   "license": "GPLv3",
   "scripts": {
-    "build": "babel src --out-dir dist",
+    "build": "babel src --extensions .js,.ts,.tsx --out-dir dist",
     "lint": "eslint --ignore-path .gitignore .",
-    "prettier": "prettier --ignore-path .gitignore \"**/*.+(js|json)\"",
+    "check-types": "tsc",
+    "prettier": "prettier --ignore-path .gitignore \"**/*.+(js|json|ts|tsx)\"",
     "format": "npm run prettier -- --write",
     "check-format": "npm run prettier -- --list-different",
-    "validate": "npm run check-format && npm run lint && npm run build"
+    "validate": "npm run check-types && npm run check-format && npm run lint && npm run build"
   },
   "devDependencies": {
     "@babel/cli": "^7.7.0",
     "@babel/core": "^7.7.2",
     "@babel/preset-env": "^7.7.1",
+    "@babel/preset-typescript": "^7.7.2",
     "eslint": "^6.6.0",
     "eslint-config-prettier": "^6.5.0",
-    "prettier": "^1.19.1"
+    "prettier": "^1.19.1",
+    "typescript": "^3.7.2"
   }
 }

src/typescript-example.js

@@ -1,14 +0,0 @@
-function add(a, b) {
-  return a + b
-}
-
-function getFullName(user) {
-  const {
-    name: {first, middle, last},
-  } = user
-  return [first, middle, last].filter(Boolean).join('')
-}
-
-add(1, 'two')
-
-getFullName({name: {first: 'Joe', midd1e: 'Bud', last: 'Matthews'}})

src/typescript-example.ts

@@ -0,0 +1,21 @@
+function add(a: number, b: number): number {
+  return a + b
+}
+
+interface User {
+  name: {
+    first: string
+    middle: string
+    last: string
+  }
+}
+function getFullName(user: User): string {
+  const {
+    name: {first, middle, last},
+  } = user
+  return [first, middle, last].filter(Boolean).join('')
+}
+
+add(1, 2)
+
+getFullName({name: {first: 'Joe', middle: 'Bud', last: 'Matthews'}})

tsconfig.json

@@ -0,0 +1,6 @@
+{
+  "compilerOptions": {
+    "noEmit": true,
+    "baseUrl": "./src"
+  }
+}