Add TypeScript and ESM support

.eslintrc

@@ -0,0 +1,39 @@
+{
+  "root": true,
+  "extends": ["eslint:recommended", "prettier"],
+  "ignorePatterns": ["lib/**"],
+
+  "overrides": [
+    {
+      "files": ["*.js"],
+      "env": {
+        "node": true
+      },
+      "parserOptions": {
+        "sourceType": "module",
+        "ecmaVersion": "latest"
+      }
+    },
+    {
+      "files": ["*.ts"],
+      "plugins": ["eslint-plugin-tsdoc"],
+      "extends": [
+        "plugin:@typescript-eslint/recommended",
+        "plugin:@typescript-eslint/recommended-requiring-type-checking",
+        "prettier"
+      ],
+      "parserOptions": {
+        "project": "tsconfig.json"
+      },
+      "rules": {
+        "tsdoc/syntax": "warn",
+        // Aligns with our style-guide.
+        "@typescript-eslint/switch-exhaustiveness-check": "error"
+      }
+    },
+    {
+      "files": ["tests.ts"],
+      "extends": ["plugin:jest/recommended"]
+    }
+  ]
+}

.github/workflows/ci.yml

@@ -2,21 +2,29 @@ name: CI
 
 on:
   push:
-    branches: [ master ]
+    branches: [master]
   pull_request:
-    branches: [ master ]
+    branches: [master]
 
 jobs:
   test:
+    name: 'Test'
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node-version: [6.x, 14.x]
+        node-version: [12.x, 16.x]
     steps:
-    - uses: actions/checkout@v2
-    - name: Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v1
-      with:
-        node-version: ${{ matrix.node-version }}
-    - run: npm install
-    - run: npm test
+      - name: Checkout
+      - uses: actions/checkout@v2
+
+      - name: Setup Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v2
+        with:
+          node-version: ${{ matrix.node-version }}
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm install
+
+      - name: Run tests
+      - run: npm test

.github/workflows/quality.yml

@@ -0,0 +1,61 @@
+name: Quality
+
+on: push
+
+jobs:
+  prettier:
+    name: 'Prettier'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v2
+        with:
+          node-version: '16'
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm install
+
+      - name: Run Prettier check
+        run: npm run prettier-check
+
+  eslint:
+    name: 'ESLint'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v2
+        with:
+          node-version: '16'
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm install
+
+      - name: Run ESLint check
+        run: npm run eslint-check
+
+  types:
+    name: 'TypeScript'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v2
+        with:
+          node-version: '16'
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm install
+
+      - name: Run TypeScript type check
+        run: npm run type-check

.gitignore

@@ -1,5 +1,8 @@
+# build
+lib/
+
 # dependencies
-node_modules
+node_modules/
 
 # logs
 npm-debug.log

.husky/pre-commit

@@ -0,0 +1,4 @@
+#!/bin/sh
+. "$(dirname "$0")/_/husky.sh"
+
+npx lint-staged