frontend: add api utility

src/web/lib/api.ts

@@ -0,0 +1,46 @@
+export interface Api {
+    delete(endpoint: string, body?: object): Promise<Response>;
+    get(endpoint: string, body?: object): Promise<Response>;
+    patch(endpoint: string, body?: object): Promise<Response>;
+    post(endpoint: string, body?: object): Promise<Response>;
+    put(endpoint: string, body?: object): Promise<Response>;
+}
+
+// we can't write these as individual functions
+// because "get" is a keyword in that context
+const api: Api = {
+    delete: (endpoint, body) => doRequest("DELETE", endpoint, body),
+    get: (endpoint, body) => doRequest("GET", endpoint, body),
+    patch: (endpoint, body) => doRequest("PATCH", endpoint, body),
+    post: (endpoint, body) => doRequest("POST", endpoint, body),
+    put: (endpoint, body) => doRequest("PUT", endpoint, body),
+};
+export default api;
+
+export type Method = "DELETE" | "GET" | "PATCH" | "POST" | "PUT";
+
+export async function doRequest(method: Method, endpoint: string, body?: object): Promise<Response> {
+    const params: RequestInit = { method };
+    const headers = [];
+    if (body !== undefined) {
+        headers.push(["Content-Type", "application/json"]);
+        params.body = JSON.stringify(body);
+    }
+    params.headers = headers;
+
+    const response = await fetch(endpoint, params);
+    if (response.ok) {
+        return response;
+    } else {
+        throw new ApiError(response);
+    }
+}
+
+export class ApiError extends Error {
+    public readonly response: Response;
+
+    constructor(response: Response) {
+        super(response.statusText);
+        this.response = response;
+    }
+}