Add TypeScript config and emit errors when building TypeScript files.

package.json

@@ -17,7 +17,7 @@
     "build": "yarn run build-css && yarn run build-js && yarn build-global-nav",
     "watch": "yarn run watch-css && yarn run watch-js",
     "watch-css": "watch -p 'static/sass/**/*.scss' -p 'node_modules/vanilla-framework/scss/**/*.scss' -c 'yarn run build-css'",
-    "watch-js": "watch -p 'static/js/src/**/*.js' -p 'static/js/src/**/*.jsx' -p 'static/js/data/**/*.js' -p 'static/js/third-party/**/*.js' -c 'yarn run build-js'",
+    "watch-js": "watch -p 'static/js/src/**/*.{js,jsx,ts,tsx}' -p 'static/js/data/**/*.js' -p 'static/js/third-party/**/*.js' -c 'yarn run build-js && tsc -noEmit'",
     "clean": "rm -rf node_modules yarn-error.log css static/css *.log *.sqlite _site/ build/ .jekyll-metadata .bundle static/js/dist etc/",
     "serve": "./entrypoint 0.0.0.0:${PORT}",
     "start": "yarn run build && concurrently --kill-others --raw 'yarn run watch-css' 'yarn run watch-js' 'yarn run serve'",
@@ -81,6 +81,7 @@
     "react-dom": "17.0.2",
     "react-query": "3.16.0",
     "smartquotes": "2.3.2",
+    "typescript": "4.3.5",
     "url-polyfill": "1.1.12",
     "url-search-params-polyfill": "8.1.0",
     "vanilla-framework": "2.32.0"

tsconfig.json

@@ -0,0 +1,27 @@
+{
+  "compilerOptions": {
+    "allowJs": true,
+    "allowSyntheticDefaultImports": true,
+    "alwaysStrict": true,
+    "baseUrl": "static/js/src",
+    "esModuleInterop": true,
+    "forceConsistentCasingInFileNames": true,
+    "isolatedModules": true,
+    "jsx": "react-jsx",
+    "lib": ["dom", "dom.iterable", "esnext"],
+    "module": "esnext",
+    "moduleResolution": "node",
+    "noEmit": true,
+    "noFallthroughCasesInSwitch": true,
+    "noImplicitReturns": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "pretty": true,
+    "resolveJsonModule": true,
+    "skipLibCheck": true,
+    "strict": true,
+    "target": "es6",
+    "types": ["node", "jest"]
+  },
+  "include": ["static/js/src"]
+}

yarn.lock

@@ -7638,6 +7638,11 @@ typedarray@^0.0.6:
   resolved "https://registry.yarnpkg.com/typedarray/-/typedarray-0.0.6.tgz#867ac74e3864187b1d3d47d996a78ec5c8830777"
   integrity sha1-hnrHTjhkGHsdPUfZlqeOxciDB3c=
 
+[email protected]:
+  version "4.3.5"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.3.5.tgz#4d1c37cc16e893973c45a06886b7113234f119f4"
+  integrity sha512-DqQgihaQ9cUrskJo9kIyW/+g0Vxsk8cDtZ52a3NGh0YNTfpUSArXSohyUGnvbPazEPLu398C0UxmKSOrPumUzA==
+
 unbox-primitive@^1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/unbox-primitive/-/unbox-primitive-1.0.1.tgz#085e215625ec3162574dc8859abee78a59b14471"