add typescript

.eslintrc

@@ -1,12 +1,21 @@
 {
+  "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"]
   },

package-lock.json

@@ -821,6 +821,76 @@
         "to-fast-properties": "^2.0.0"
       }
     },
+    "@types/eslint-visitor-keys": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/@types/eslint-visitor-keys/-/eslint-visitor-keys-1.0.0.tgz",
+      "integrity": "sha512-OCutwjDZ4aFS6PB1UZ988C4YgwlBHJd6wCeQqaLdmadZ/7e+w79+hbMUFC1QXDNCmdyoRfAFdm0RypzwR+Qpag==",
+      "dev": true
+    },
+    "@types/json-schema": {
+      "version": "7.0.3",
+      "resolved": "https://registry.npmjs.org/@types/json-schema/-/json-schema-7.0.3.tgz",
+      "integrity": "sha512-Il2DtDVRGDcqjDtE+rF8iqg1CArehSK84HZJCT7AMITlyXRBpuPhqGLDQMowraqqu1coEaimg4ZOqggt6L6L+A==",
+      "dev": true
+    },
+    "@typescript-eslint/eslint-plugin": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/eslint-plugin/-/eslint-plugin-2.0.0.tgz",
+      "integrity": "sha512-Mo45nxTTELODdl7CgpZKJISvLb+Fu64OOO2ZFc2x8sYSnUpFrBUW3H+H/ZGYmEkfnL6VkdtOSxgdt+Av79j0sA==",
+      "dev": true,
+      "requires": {
+        "@typescript-eslint/experimental-utils": "2.0.0",
+        "eslint-utils": "^1.4.0",
+        "functional-red-black-tree": "^1.0.1",
+        "regexpp": "^2.0.1",
+        "tsutils": "^3.14.0"
+      }
+    },
+    "@typescript-eslint/experimental-utils": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/experimental-utils/-/experimental-utils-2.0.0.tgz",
+      "integrity": "sha512-XGJG6GNBXIEx/mN4eTRypN/EUmsd0VhVGQ1AG+WTgdvjHl0G8vHhVBHrd/5oI6RRYBRnedNymSYWW1HAdivtmg==",
+      "dev": true,
+      "requires": {
+        "@types/json-schema": "^7.0.3",
+        "@typescript-eslint/typescript-estree": "2.0.0",
+        "eslint-scope": "^4.0.0"
+      },
+      "dependencies": {
+        "eslint-scope": {
+          "version": "4.0.3",
+          "resolved": "https://registry.npmjs.org/eslint-scope/-/eslint-scope-4.0.3.tgz",
+          "integrity": "sha512-p7VutNr1O/QrxysMo3E45FjYDTeXBy0iTltPFNSqKAIfjDSXC+4dj+qfyuD8bfAXrW/y6lW3O76VaYNPKfpKrg==",
+          "dev": true,
+          "requires": {
+            "esrecurse": "^4.1.0",
+            "estraverse": "^4.1.1"
+          }
+        }
+      }
+    },
+    "@typescript-eslint/parser": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/parser/-/parser-2.0.0.tgz",
+      "integrity": "sha512-ibyMBMr0383ZKserIsp67+WnNVoM402HKkxqXGlxEZsXtnGGurbnY90pBO3e0nBUM7chEEOcxUhgw9aPq7fEBA==",
+      "dev": true,
+      "requires": {
+        "@types/eslint-visitor-keys": "^1.0.0",
+        "@typescript-eslint/experimental-utils": "2.0.0",
+        "@typescript-eslint/typescript-estree": "2.0.0",
+        "eslint-visitor-keys": "^1.0.0"
+      }
+    },
+    "@typescript-eslint/typescript-estree": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/typescript-estree/-/typescript-estree-2.0.0.tgz",
+      "integrity": "sha512-NXbmzA3vWrSgavymlzMWNecgNOuiMMp62MO3kI7awZRLRcsA1QrYWo6q08m++uuAGVbXH/prZi2y1AWuhSu63w==",
+      "dev": true,
+      "requires": {
+        "lodash.unescape": "4.0.1",
+        "semver": "^6.2.0"
+      }
+    },
     "acorn": {
       "version": "6.2.1",
       "resolved": "https://registry.npmjs.org/acorn/-/acorn-6.2.1.tgz",
@@ -2943,6 +3013,12 @@
       "integrity": "sha512-8xOcRHvCjnocdS5cpwXQXVzmmh5e5+saE2QGoeQmbKmRS6J3VQppPOIt0MnmE+4xlZoumy0GPG0D0MVIQbNA1A==",
       "dev": true
     },
+    "lodash.unescape": {
+      "version": "4.0.1",
+      "resolved": "https://registry.npmjs.org/lodash.unescape/-/lodash.unescape-4.0.1.tgz",
+      "integrity": "sha1-vyJJiGzlFM2hEvrpIYzcBlIR/Jw=",
+      "dev": true
+    },
     "loose-envify": {
       "version": "1.4.0",
       "resolved": "https://registry.npmjs.org/loose-envify/-/loose-envify-1.4.0.tgz",
@@ -4062,6 +4138,15 @@
       "integrity": "sha512-qOebF53frne81cf0S9B41ByenJ3/IuH8yJKngAX35CmiZySA0khhkovshKK+jGCaMnVomla7gVlIcc3EvKPbTQ==",
       "dev": true
     },
+    "tsutils": {
+      "version": "3.17.1",
+      "resolved": "https://registry.npmjs.org/tsutils/-/tsutils-3.17.1.tgz",
+      "integrity": "sha512-kzeQ5B8H3w60nFY2g8cJIuH7JDpsALXySGtwGJ0p2LSjLgay3NdIpqq5SoOBe46bKDW2iq25irHCr8wjomUS2g==",
+      "dev": true,
+      "requires": {
+        "tslib": "^1.8.1"
+      }
+    },
     "type-check": {
       "version": "0.3.2",
       "resolved": "https://registry.npmjs.org/type-check/-/type-check-0.3.2.tgz",
@@ -4071,6 +4156,12 @@
         "prelude-ls": "~1.1.2"
       }
     },
+    "typescript": {
+      "version": "3.5.3",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-3.5.3.tgz",
+      "integrity": "sha512-ACzBtm/PhXBDId6a6sDJfroT2pOWt/oOnk4/dElG5G33ZL776N3Y6/6bKZJBFpd+b05F3Ct9qDjMeJmRWtE2/g==",
+      "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

@@ -5,18 +5,22 @@
   "license": "GPLv3",
   "scripts": {
     "build": "babel src --out-dir dist",
-    "lint": "eslint --ignore-path .gitignore .",
+    "lint": "eslint --ignore-path .gitignore --ext .js,.ts,.tsx .",
+    "check-types": "tsc",
     "prettier": "prettier --ignore-path .gitignore --write \"**/*.+(js|json)\"",
     "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": "^7.5.5",
     "@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",
-    "prettier": "^1.18.2"
+    "prettier": "^1.18.2",
+    "typescript": "^3.5.3"
   }
 }

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 +1,9 @@
+{
+  "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"
+  }
+}