add support for signal request option

src/request/interfaces.d.ts

@@ -1,3 +1,4 @@
+import { AbortSignal } from '@dojo/shim/AbortController';
 import { IterableIterator } from '@dojo/shim/iterator';
 import Task from '../async/Task';
 import UrlSearchParams, { ParamList } from '../UrlSearchParams';
@@ -57,6 +58,10 @@ export interface RequestOptions {
 	 * Password for HTTP authentication
 	 */
 	password?: string;
+	/**
+	 * Abort signal, allowing for cancelable requests
+	 */
+	signal?: AbortSignal;
 	/**
 	 * Number of milliseconds before the request times out and is canceled
 	 */

src/request/providers/node.ts

@@ -654,6 +654,15 @@ export default function node(url: string, options: NodeRequestOptions = {}): Upl
 					timeoutReject && timeoutReject(new TimeoutError('The request timed out'));
 				}, options.timeout);
 			}
+
+			if (options.signal) {
+				options.signal.addEventListener('abort', () => {
+					const abortError = new Error('Aborted');
+					abortError.name = 'AbortError';
+					reject(abortError);
+				});
+			}
+
 		},
 		() => {
 			request.abort();

src/request/providers/xhr.ts

@@ -205,6 +205,19 @@ export default function xhr(url: string, options: XhrRequestOptions = {}): Uploa
 	const task = <UploadObservableTask<XhrResponse>>new Task<XhrResponse>((resolve, reject) => {
 		timeoutReject = reject;
 
+		if (options.signal) {
+			options.signal.addEventListener('abort', () => {
+				let abortError: Error;
+				try {
+					abortError = new DOMException('Aborted', 'AbortError');
+				} catch {
+					abortError = new Error('Aborted');
+					abortError.name = 'AbortError';
+				}
+				reject(new DOMException('Aborted', 'AbortError'));
+			});
+		}
+
 		request.onreadystatechange = function() {
 			if (isAborted) {
 				return;

tests/unit/request/node.ts

@@ -7,6 +7,7 @@ import * as zlib from 'zlib';
 import { Response } from '../../../src/request/interfaces';
 import { default as nodeRequest, NodeResponse } from '../../../src/request/providers/node';
 import TimeoutError from '../../../src/request/TimeoutError';
+import AbortController from '@dojo/shim/AbortController';
 
 const serverPort = 8124;
 const serverUrl = 'http://localhost:' + serverPort;
@@ -463,6 +464,20 @@ registerSuite('request/node', {
 				);
 			},
 
+			signal(this: any) {
+				const dfd = this.async();
+				const url = getRequestUrl('foo.json');
+				const controller = new AbortController();
+				const { signal } = controller;
+				const request = nodeRequest(url, { signal });
+				request.catch(
+					dfd.callback((error: Error) => {
+						assert.strictEqual(error.name, 'AbortError');
+					})
+				);
+				controller.abort();
+			},
+
 			'user and password': {
 				both(this: any): void {
 					const user = 'user name';

tests/unit/request/xhr.ts

@@ -1,6 +1,7 @@
 const { registerSuite } = intern.getInterface('object');
 const { assert } = intern.getPlugin('chai');
 
+import AbortController from '@dojo/shim/AbortController';
 import xhrRequest, { XhrResponse } from '../../../src/request/providers/xhr';
 import { Response } from '../../../src/request/interfaces';
 import UrlSearchParams from '../../../src/UrlSearchParams';
@@ -94,6 +95,23 @@ registerSuite('request/providers/xhr', {
 				);
 			},
 
+			'"signal"'(this: any) {
+				if (!echoServerAvailable) {
+					this.skip('No echo server available');
+				}
+				const dfd = this.async();
+				const controller = new AbortController();
+				const { signal } = controller;
+				const request = xhrRequest('/__echo/foo.json', { signal, timeout: 100 });
+				request.catch(
+					dfd.callback((error: Error) => {
+						assert.strictEqual(error.name, 'AbortError');
+					})
+				);
+
+				controller.abort();
+			},
+
 			'user and password'(this: any) {
 				if (!echoServerAvailable) {
 					this.skip('No echo server available');