FetchHandler.ts

import RelativeURL from '../location/RelativeURL';
import IRequestInit from './IRequestInit';
import IDocument from '../nodes/document/IDocument';
import IResponse from './IResponse';
import Response from './Response';
import NodeFetch from 'node-fetch';

/**
 * Helper class for performing fetch.
 */
export default class FetchHandler {
	/**
	 * Returns resource data asynchronously.
	 *
	 * @param document Document.
	 * @param url URL to resource.
	 * @param [init] Init.
	 * @returns Response.
	 */
	public static fetch(document: IDocument, url: string, init?: IRequestInit): Promise<IResponse> {
		// We want to only load NodeFetch when it is needed to improve performance and not have direct dependencies to server side packages.
		const taskManager = document.defaultView.happyDOM.asyncTaskManager;
		const requestInit = { ...init, headers: { ...init?.headers } };

		// We need set referer to solve anti-hotlinking.
		// And the browser will set the referer to the origin of the page.
		requestInit.headers['referer'] = document.defaultView.location.origin;

		requestInit.headers['user-agent'] = document.defaultView.navigator.userAgent;
		requestInit.headers['cookie'] = document.defaultView.document.cookie;

		return new Promise((resolve, reject) => {
			const taskID = taskManager.startTask();

			NodeFetch(RelativeURL.getAbsoluteURL(document.defaultView.location, url).href, requestInit)
				.then((response) => {
					if (taskManager.getTaskCount() === 0) {
						reject(new Error('Failed to complete fetch request. Task was canceled.'));
					} else {
						response.constructor['_ownerDocument'] = document;

						for (const key of Object.keys(Response.prototype)) {
							if (Response.prototype.hasOwnProperty(key) && key !== 'constructor') {
								if (typeof Response.prototype[key] === 'function') {
									response[key] = Response.prototype[key].bind(response);
								} else {
									response[key] = Response.prototype[key];
								}
							}
						}

						taskManager.endTask(taskID);
						resolve(response);
					}
				})
				.catch((error) => {
					reject(error);
					taskManager.cancelAll(error);
				});
		});
	}
}