build: add types to the build via checkJs

Author: jrolfs

package.json

@@ -13,7 +13,9 @@
   "scripts": {
     "test": "node src test",
     "test:update": "node src test --updateSnapshot",
-    "build": "node src build",
+    "build": "run-p build:*",
+    "build:source": "node src build",
+    "build:types": "tsc -p src/",
     "lint": "node src lint",
     "format": "node src format",
     "validate": "node src validate",

src/tsconfig.json

@@ -0,0 +1,12 @@
+{
+  "extends": "./config/tsconfig.json",
+  "include": ["./api"],
+  "compilerOptions": {
+    "allowJs": true,
+    "checkJs": true,
+    "declaration": true,
+    "noEmit": false,
+    "outDir": "../dist",
+    "rootDir": "."
+  }
+}