Migrate APIRoutesService to TS

src/sidebar/services/api-routes.js → src/sidebar/services/api-routes.ts

+import type {
+  IndexResponse,
+  LinksResponse,
+  RouteMap,
+  RouteMetadata,
+} from '../../types/api';
+import type { SidebarSettings } from '../../types/config';
 import { fetchJSON } from '../util/fetch';
 import { retryPromiseOperation } from '../util/retry';
 
 /**
  * Fetch an API metadata file, retrying the operation if it fails.
- *
- * @param {string} url
  */
-function getJSON(url) {
-  return retryPromiseOperation(() =>
+function getJSON<T>(url: string): Promise<T> {
+  return retryPromiseOperation(
+    () =>
       // nb. The `/api/` and `/api/links` routes are fetched without specifying
       // any additional headers/config so that we can use `<link rel="preload">` in
       // the `/app.html` response to fetch them early, while the client JS app
       // is loading.
-    fetchJSON(url)
+      fetchJSON(url) as Promise<T>
   );
 }
 
-/**
- * @typedef {import('../../types/api').IndexResponse} IndexResponse
- * @typedef {import('../../types/api').LinksResponse} LinksResponse
- * @typedef {import('../../types/api').RouteMap} RouteMap
- * @typedef {import('../../types/api').RouteMetadata} RouteMetadata
- * @typedef {import('../../types/config').SidebarSettings} SidebarSettings
- */
-
 /**
  * A service which fetches and caches API route metadata.
  */
 // @inject
 export class APIRoutesService {
-  /**
-   * @param {SidebarSettings} settings
-   */
-  constructor(settings) {
-    this._apiURL = settings.apiUrl;
+  private _apiURL: SidebarSettings['apiUrl'];
+  private _routeCache: Promise<RouteMap> | null;
+  private _linkCache: Promise<LinksResponse> | null;
 
-    /** @type {Promise<RouteMap>|null} */
+  constructor(settings: SidebarSettings) {
+    this._apiURL = settings.apiUrl;
     this._routeCache = null;
-
-    /** @type {Promise<LinksResponse>|null} */
     this._linkCache = null;
   }
 
@@ -48,29 +43,25 @@ export class APIRoutesService {
    * Routes are fetched without any authentication and therefore assumed to be
    * the same regardless of whether the user is authenticated or not.
    *
-   * @return {Promise<RouteMap>} - Map of routes to route metadata.
+   * @return Map of routes to route metadata.
    */
-  routes() {
+  routes(): Promise<RouteMap> {
     if (!this._routeCache) {
-      this._routeCache = getJSON(this._apiURL).then(result => {
-        const index = /** @type {IndexResponse} */ (result);
-        return index.links;
-      });
+      this._routeCache = getJSON<IndexResponse>(this._apiURL).then(
+        result => result.links
+      );
     }
     return this._routeCache;
   }
 
   /**
    * Fetch and cache service page links from the API.
-   *
-   * @return {Promise<LinksResponse>}
    */
-  links() {
+  links(): Promise<LinksResponse> {
     if (!this._linkCache) {
       this._linkCache = this.routes().then(async routes => {
-        const linksRoute = /** @type {RouteMetadata} */ (routes.links);
-        const links = await getJSON(linksRoute.url);
-        return /** @type {LinksResponse} */ (links);
+        const linksRoute = routes.links as RouteMetadata;
+        return getJSON<LinksResponse>(linksRoute.url);
       });
     }
     return this._linkCache;