TypeScript

Type definitions ship with the package and need TypeScript 5.2 or newer. Besides WasmClient, it exports the option and result types ClientOptions, RequestOptions, BrowserRequestOptions, FetchInit, RetryOptions, RetryBudgetOptions, HttpResponse, RustFetchError, RustFetchErrorKind, DownloadProgress, UploadProgress, HeadersLike, QueryParams, RequestBody, ResponseBodyType and RedirectMode, for interceptors InterceptedRequest, RequestInterceptor, ResponseFulfilledInterceptor and ResponseRejectedInterceptor, for WebSockets WebSocketConnection, WebSocketOptions, ReconnectOptions, WebSocketCloseInfo, WebSocketReconnectInfo, WebSocketState and WebSocketData, and for Server-Sent Events EventStream, EventStreamOptions, EventStreamState and ServerSentEvent.

Every request method takes the response body's type as a type parameter, defaulting to any:

import { WasmClient, type HttpResponse, type RustFetchError } from 'rust-fetch';

const client = new WasmClient({ baseUrl: 'https://api.example.com/v1' });

interface User { id: number; name: string }

const res = await client.get<User>('/users/42'); // HttpResponse<User>
res.body.name; // string

const created: HttpResponse<User> = await client.post<User>('/users', { body: { name: 'Zoë' } });

try {
  await client.get('/users/9');
} catch (e) {
  const error = e as RustFetchError;
  if (error.kind === 'HttpError') console.log(error.status);
}

The type parameter describes what you expect; rust-fetch doesn't check the JSON against it. Validate untrusted responses with a schema library if you need to.

Legacy functions

These standalone functions still work. Each call uses a default client: 30 s timeout, no retries.

Function	Resolves to
fetch_json(url) / fetch_json_promise(url)	Parsed JSON, whatever the Content-Type; null for an empty body
fetch_text(url)	The body as a string
fetch_with_options(url, method, headers, body?)	The full HttpResponse
create_client()	new WasmClient()
fetch_wasm_json, fetch_wasm_map, fetch_wasm_api, fetch_wasm_html	Deprecated aliases of fetch_json / fetch_text