Migrate fetch module to TS

src/sidebar/util/fetch.js → src/sidebar/util/fetch.ts

@@ -8,16 +8,19 @@
  *  - Failures to parse the response in the expected format (eg. JSON)
  */
 export class FetchError extends Error {
+  url: string;
+  response: Response | null;
+  reason: string;
+
   /**
-   * @param {string} url - The URL that was requested. This may be different
-   *   than the final URL of the response if a redirect happened.
-   * @param {Response|null} response - The response to the `fetch` request or
-   *   `null` if the fetch failed
-   * @param {string} [reason] - Additional details about the error. This might
-   *   include context of the network request or a server-provided error in
-   *   the response.
+   * @param url - The URL that was requested. This may be different than the
+   *   final URL of the response if a redirect happened.
+   * @param response - The response to the `fetch` request or `null` if the
+   *   fetch failed
+   * @param reason - Additional details about the error. This might include
+   *   context of the network request or a server-provided error in the response.
    */
-  constructor(url, response, reason = '') {
+  constructor(url: string, response: Response | null, reason = '') {
     let message = 'Network request failed';
     if (response) {
       message += ` (${response.status})`;
@@ -39,13 +42,15 @@ export class FetchError extends Error {
  * fetchJSON wraps the browser's `fetch` API to standardize error handling when
  * making network requests that return JSON responses.
  *
- * @param {string} url
- * @param {RequestInit} [init] - Parameters for `fetch` request
- * @return {Promise<unknown>} - Parsed JSON response or `null` if response status is 204 (No Content)
+ * @param init - Parameters for `fetch` request
+ * @return Parsed JSON response or `null` if response status is 204 (No Content)
  * @throws {FetchError} if the request fails, returns a non-2xx status or a JSON
  *   response is expected but cannot be parsed
  */
-export async function fetchJSON(url, init) {
+export async function fetchJSON(
+  url: string,
+  init?: RequestInit
+): Promise<unknown> {
   let response;
   try {
     response = await fetch(url, init);