import { Observable } from 'rxjs';
import { SafeAny } from '@ngify/core';
import { HttpBackend } from './backend';
import { HttpRequest } from './request';
import { HttpEvent } from './response';
/**
 * Uses `fetch` to send requests to a backend server.
 *
 * This `FetchBackend` requires the support of the
 * [Fetch API](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API) which is available on all
 * supported browsers and on Node.js v18 or later.
 *
 * @see {@link HttpHandler}
 *
 * @publicApi
 */
export declare class HttpFetchBackend implements HttpBackend {
    private fetchImpl;
    constructor(fetchImpl?: typeof fetch);
    handle(request: HttpRequest<SafeAny>): Observable<HttpEvent<SafeAny>>;
    private doRequest;
    private parseBody;
    private createRequestInit;
    private concatChunks;
}