feat: [#1502] Allow fetch to be intercepted and modified

packages/happy-dom/src/browser/types/IBrowserSettings.ts

@@ -1,5 +1,6 @@
 import BrowserErrorCaptureEnum from '../enums/BrowserErrorCaptureEnum.js';
 import BrowserNavigationCrossOriginPolicyEnum from '../enums/BrowserNavigationCrossOriginPolicyEnum.js';
+import IFetchInterceptor from '../../fetch/types/IFetchInterceptor.js';
 
 /**
  * Browser settings.
@@ -40,6 +41,8 @@ export default interface IBrowserSettings {
 		 * @see https://developer.mozilla.org/en-US/docs/Web/Security/Same-origin_policy
 		 */
 		disableSameOriginPolicy: boolean;
+
+		interceptor?: IFetchInterceptor;
 	};
 
 	/**

packages/happy-dom/src/browser/types/IOptionalBrowserSettings.ts

@@ -1,5 +1,6 @@
 import BrowserErrorCaptureEnum from '../enums/BrowserErrorCaptureEnum.js';
 import BrowserNavigationCrossOriginPolicyEnum from '../enums/BrowserNavigationCrossOriginPolicyEnum.js';
+import IFetchInterceptor from '../../fetch/types/IFetchInterceptor.js';
 
 export default interface IOptionalBrowserSettings {
 	/** Disables JavaScript evaluation. */
@@ -34,6 +35,8 @@ export default interface IOptionalBrowserSettings {
 		 * @see https://developer.mozilla.org/en-US/docs/Web/Security/Same-origin_policy
 		 */
 		disableSameOriginPolicy?: boolean;
+
+		interceptor?: IFetchInterceptor;
 	};
 
 	/**

packages/happy-dom/src/fetch/Fetch.ts

@@ -26,6 +26,7 @@ import FetchResponseHeaderUtility from './utilities/FetchResponseHeaderUtility.j
 import FetchHTTPSCertificate from './certificate/FetchHTTPSCertificate.js';
 import { Buffer } from 'buffer';
 import FetchBodyUtility from './utilities/FetchBodyUtility.js';
+import IFetchInterceptor from './types/IFetchInterceptor.js';
 
 const LAST_CHUNK = Buffer.from('0\r\n\r\n');
 
@@ -39,7 +40,7 @@ const LAST_CHUNK = Buffer.from('0\r\n\r\n');
  */
 export default class Fetch {
 	private reject: (reason: Error) => void | null = null;
-	private resolve: (value: Response | Promise<Response>) => void | null = null;
+	private resolve: (value: Response | Promise<Response>) => Promise<void> = null;
 	private listeners = {
 		onSignalAbort: this.onSignalAbort.bind(this)
 	};
@@ -50,6 +51,7 @@ export default class Fetch {
 	private nodeResponse: IncomingMessage | null = null;
 	private response: Response | null = null;
 	private responseHeaders: Headers | null = null;
+	private interceptor?: IFetchInterceptor;
 	private request: Request;
 	private redirectCount = 0;
 	private disableCache: boolean;
@@ -99,6 +101,7 @@ export default class Fetch {
 			options.disableSameOriginPolicy ??
 			this.#browserFrame.page.context.browser.settings.fetch.disableSameOriginPolicy ??
 			false;
+		this.interceptor = this.#browserFrame.page.context.browser.settings.fetch.interceptor;
 	}
 
 	/**
@@ -108,6 +111,15 @@ export default class Fetch {
 	 */
 	public async send(): Promise<Response> {
 		FetchRequestReferrerUtility.prepareRequest(new URL(this.#window.location.href), this.request);
+		const beforeRequestResponse = this.interceptor?.beforeAsyncRequest
+			? await this.interceptor.beforeAsyncRequest({
+					request: this.request,
+					window: this.#window
+				})
+			: undefined;
+		if (beforeRequestResponse instanceof Response) {
+			return beforeRequestResponse;
+		}
 		FetchRequestValidationUtility.validateSchema(this.request);
 
 		if (this.request.signal.aborted) {
@@ -122,7 +134,14 @@ export default class Fetch {
 			this.response = new this.#window.Response(result.buffer, {
 				headers: { 'Content-Type': result.type }
 			});
-			return this.response;
+			const interceptedResponse = this.interceptor.afterAsyncResponse
+				? await this.interceptor.afterAsyncResponse({
+						window: this.#window,
+						response: this.response,
+						request: this.request
+					})
+				: undefined;
+			return interceptedResponse instanceof Response ? interceptedResponse : this.response;
 		}
 
 		// Security check for "https" to "http" requests.
@@ -365,9 +384,9 @@ export default class Fetch {
 				throw new this.#window.Error('Fetch already sent.');
 			}
 
-			this.resolve = (response: Response | Promise<Response>): void => {
+			this.resolve = async (response: Response | Promise<Response>): Promise<void> => {
 				// We can end up here when closing down the browser frame and there is an ongoing request.
-				// Therefore we need to check if browserFrame.page.context is still available.
+				// Therefore, we need to check if browserFrame.page.context is still available.
 				if (
 					!this.disableCache &&
 					response instanceof Response &&
@@ -383,7 +402,14 @@ export default class Fetch {
 						});
 				}
 				this.#browserFrame[PropertySymbol.asyncTaskManager].endTask(taskID);
-				resolve(response);
+				const interceptedResponse = this.interceptor.afterAsyncResponse
+					? await this.interceptor.afterAsyncResponse({
+							window: this.#window,
+							response: await response,
+							request: this.request
+						})
+					: undefined;
+				resolve(interceptedResponse instanceof Response ? interceptedResponse : response);
 			};
 			this.reject = (error: Error): void => {
 				this.#browserFrame[PropertySymbol.asyncTaskManager].endTask(taskID);

packages/happy-dom/src/fetch/SyncFetch.ts

@@ -20,6 +20,7 @@ import Zlib from 'zlib';
 import FetchResponseRedirectUtility from './utilities/FetchResponseRedirectUtility.js';
 import FetchCORSUtility from './utilities/FetchCORSUtility.js';
 import Fetch from './Fetch.js';
+import IFetchInterceptor from './types/IFetchInterceptor.js';
 
 interface ISyncHTTPResponse {
 	error: string;
@@ -39,6 +40,7 @@ export default class SyncFetch {
 	private redirectCount = 0;
 	private disableCache: boolean;
 	private disableSameOriginPolicy: boolean;
+	private interceptor?: IFetchInterceptor;
 	#browserFrame: IBrowserFrame;
 	#window: BrowserWindow;
 	#unfilteredHeaders: Headers | null = null;
@@ -84,6 +86,7 @@ export default class SyncFetch {
 			options.disableSameOriginPolicy ??
 			this.#browserFrame.page.context.browser.settings.fetch.disableSameOriginPolicy ??
 			false;
+		this.interceptor = this.#browserFrame.page.context.browser.settings.fetch.interceptor;
 	}
 
 	/**
@@ -93,6 +96,15 @@ export default class SyncFetch {
 	 */
 	public send(): ISyncResponse {
 		FetchRequestReferrerUtility.prepareRequest(new URL(this.#window.location.href), this.request);
+		const beforeRequestResponse = this.interceptor?.beforeSyncRequest
+			? this.interceptor.beforeSyncRequest({
+					request: this.request,
+					window: this.#window
+				})
+			: undefined;
+		if (typeof beforeRequestResponse === 'object') {
+			return beforeRequestResponse;
+		}
 		FetchRequestValidationUtility.validateSchema(this.request);
 
 		if (this.request.signal.aborted) {
@@ -104,7 +116,7 @@ export default class SyncFetch {
 
 		if (this.request[PropertySymbol.url].protocol === 'data:') {
 			const result = DataURIParser.parse(this.request.url);
-			return {
+			const response = {
 				status: 200,
 				statusText: 'OK',
 				ok: true,
@@ -113,6 +125,14 @@ export default class SyncFetch {
 				headers: new Headers({ 'Content-Type': result.type }),
 				body: result.buffer
 			};
+			const interceptedResponse = this.interceptor.afterSyncResponse
+				? this.interceptor.afterSyncResponse({
+						window: this.#window,
+						response,
+						request: this.request
+					})
+				: undefined;
+			return typeof interceptedResponse === 'object' ? interceptedResponse : response;
 		}
 
 		// Security check for "https" to "http" requests.
@@ -416,7 +436,14 @@ export default class SyncFetch {
 			});
 		}
 
-		return redirectedResponse;
+		const interceptedResponse = this.interceptor.afterSyncResponse
+			? this.interceptor.afterSyncResponse({
+					window: this.#window,
+					response: redirectedResponse,
+					request: this.request
+				})
+			: undefined;
+		return typeof interceptedResponse === 'object' ? interceptedResponse : redirectedResponse;
 	}
 
 	/**

packages/happy-dom/src/fetch/types/IFetchInterceptor.ts

@@ -0,0 +1,60 @@
+import Request from '../Request.js';
+import BrowserWindow from '../../window/BrowserWindow.js';
+import Response from '../Response.js';
+import ISyncResponse from './ISyncResponse.js';
+
+export default interface IFetchInterceptor {
+	/**
+	 * Hook dispatched before making an async request.
+	 * It can be used for modifying the request, providing a response without making a request or for logging.
+	 *
+	 * @param context Contains the request and the window from where the request was made.
+	 *
+	 * @returns Promise that can resolve to a response to be used instead of sending out the response.
+	 */
+	beforeAsyncRequest?: (context: {
+		request: Request;
+		window: BrowserWindow;
+	}) => Promise<Response | void>;
+
+	/**
+	 * Hook dispatched before making an sync request.
+	 * It can be used for modifying the request, providing a response without making a request or for logging.
+	 *
+	 * @param context Contains the request and the window from where the request was made.
+	 *
+	 * @returns Promise that can resolve to a response to be used instead of sending out the response.
+	 */
+	beforeSyncRequest?: (context: {
+		request: Request;
+		window: BrowserWindow;
+	}) => ISyncResponse | void;
+
+	/**
+	 * Hook dispatched after receiving an async response.
+	 * It can be used for modifying or replacing the response and logging.
+	 *
+	 * @param context Contains the request, response and the window from where the request was made.
+	 *
+	 * @returns Promise that can resolve to a response to be used instead of sending out the response.
+	 */
+	afterAsyncResponse?: (context: {
+		request: Request;
+		response: Response;
+		window: BrowserWindow;
+	}) => Promise<Response | void>;
+
+	/**
+	 * Hook dispatched after receiving a sync response.
+	 * It can be used for modifying or replacing the response and logging
+	 *
+	 * @param context Contains the request, response and the window from where the request was made.
+	 *
+	 * @returns Promise that can resolve to a response to be used instead of sending out the response.
+	 */
+	afterSyncResponse?: (context: {
+		request: Request;
+		response: ISyncResponse;
+		window: BrowserWindow;
+	}) => ISyncResponse | void;
+}

packages/happy-dom/src/index.ts

@@ -57,6 +57,8 @@ import AbortSignal from './fetch/AbortSignal.js';
 import Headers from './fetch/Headers.js';
 import Request from './fetch/Request.js';
 import Response from './fetch/Response.js';
+import IFetchInterceptor from './fetch/types/IFetchInterceptor.js';
+import ISyncResponse from './fetch/types/ISyncResponse.js';
 import Blob from './file/Blob.js';
 import File from './file/File.js';
 import FileReader from './file/FileReader.js';
@@ -206,6 +208,8 @@ import type ITouchEventInit from './event/events/ITouchEventInit.js';
 import type IWheelEventInit from './event/events/IWheelEventInit.js';
 
 export type {
+	IFetchInterceptor,
+	ISyncResponse,
 	IAnimationEventInit,
 	IBrowser,
 	IBrowserContext,