website: typescript config updates

- Added tsconfig file.
- Set esbuild target.
- Updated eslint rules for JSDoc.

Change-Id: I212bdd58a56540da26cccc8af319a8d98fa9f35a
Reviewed-on: https://go-review.googlesource.com/c/website/+/376074
Trust: Jamal Carvalho <jamalcarvalho@google.com>
Reviewed-by: Alex Rakoczy <alex@golang.org>

.eslintrc.yaml

@@ -18,3 +18,9 @@ overrides:
       - eslint:recommended
       - plugin:@typescript-eslint/recommended
       - plugin:prettier/recommended
+    rules:
+      valid-jsdoc:
+        - error
+        - requireParamType: false
+          requireReturnType: false
+          requireReturn: false

internal/web/site.go

@@ -652,6 +652,7 @@ func (s *Site) serveTypeScript(w http.ResponseWriter, r *http.Request) {
 	}
 	result := api.Transform(contents.String(), api.TransformOptions{
 		Loader: api.LoaderTS,
+		Target: api.ES2018,
 	})
 	var buf bytes.Buffer
 	for _, v := range result.Errors {

tsconfig.json

@@ -0,0 +1,22 @@
+{
+  "compilerOptions": {
+    /* Visit https://aka.ms/tsconfig.json to read more about this file */
+    "target": "es2018",
+    "isolatedModules": true,
+    "esModuleInterop": true,
+    "forceConsistentCasingInFileNames": true,
+    "strict": true,
+    "noImplicitAny": true,
+    "noImplicitThis": true,
+    "useUnknownInCatchVariables": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "exactOptionalPropertyTypes": true,
+    "noImplicitReturns": true,
+    "noFallthroughCasesInSwitch": true,
+    "noUncheckedIndexedAccess": true,
+    "noImplicitOverride": true,
+    "noPropertyAccessFromIndexSignature": true,
+    "skipLibCheck": true,
+  }
+}