Adding fetch implementation of request api, issue #139 (#243)

* Adding fetch implementation of request api, issue #139

* Retyping fetch response body

* Fixing warning

* Code style changes

* Code style changes

* Fixing typo

* Removing iterator usage because it isnt supported in FF 39

* Style fixes

src/request/fetch.ts

@@ -0,0 +1,129 @@
+import Promise from 'dojo-shim/Promise';
+import RequestTimeoutError from './errors/RequestTimeoutError';
+import Task from '../async/Task';
+import { Handle } from '../interfaces';
+import { createHandle } from '../lang';
+import { RequestOptions, Response as RequestResponse, ResponsePromise } from '../request';
+import { generateRequestUrl } from './util';
+
+declare class Headers {
+	append(name: string, value: string): void;
+}
+
+declare class Request {
+	constructor(url: string, options?: any);
+}
+
+declare function fetch(_: any): any;
+
+export interface FetchRequestOptions extends RequestOptions {
+}
+
+export default function fetchRequest<T>(url: string, options: FetchRequestOptions = {}): ResponsePromise<T> {
+	const fetchRequestOptions: any = {};
+	const fetchRequestHeaders: Headers = new Headers();
+	const requestUrl = generateRequestUrl(url, options);
+
+	if ((!options.user || !options.password) && options.auth) {
+		const auth = options.auth.split(':');
+		options.user = decodeURIComponent(auth[ 0 ]);
+		options.password = decodeURIComponent(auth[ 1 ]);
+	}
+
+	if (options.user || options.password) {
+		fetchRequestHeaders.append('authorization', `Basic ${btoa(`${options.user}:${options.password}`)}`);
+	}
+
+	if (options.cacheBust) {
+		fetchRequestOptions.cache = 'reload';
+	}
+
+	if (!options.method) {
+		options.method = 'GET';
+	}
+
+	fetchRequestOptions.method = options.method;
+
+	if (options.headers) {
+		const headers = options.headers;
+		let hasContentTypeHeader = false;
+		let hasRequestedWithHeader = false;
+
+		for (const header in headers) {
+			if (header.toLowerCase() === 'content-type') {
+				hasContentTypeHeader = true;
+			} else if (header.toLowerCase() === 'x-requested-with') {
+				hasRequestedWithHeader = true;
+			}
+			fetchRequestHeaders.append(header.toLowerCase(), headers[ header ]);
+		}
+	}
+
+	if (options.data) {
+		fetchRequestOptions.body = options.data;
+	}
+
+	fetchRequestOptions.headers = fetchRequestHeaders;
+
+	let request = new Request(requestUrl, fetchRequestOptions);
+
+	return new Task<RequestResponse<T>>((resolve, reject) => {
+		let timeout: Handle;
+
+		fetch(request).then((fetchResponse: any) => {
+			timeout && timeout.destroy();
+
+			const { responseType = '' } = options;
+			let body: Promise<any>;
+
+			switch (responseType) {
+				case 'arraybuffer':
+					body = fetchResponse.arrayBuffer();
+					break;
+
+				case 'blob':
+					body = fetchResponse.blob();
+					break;
+
+				case 'xml':
+					body = fetchResponse.text()
+						.then((asText: string) => {
+							const parser = new DOMParser();
+							return parser.parseFromString(asText, 'text/xml');
+						});
+					break;
+
+				default:
+					body = fetchResponse.text();
+					break;
+			}
+
+			body.then((body: any) => {
+				resolve({
+					statusCode: fetchResponse.status,
+					statusText: fetchResponse.statusText,
+					data: body,
+					url: requestUrl,
+					nativeResponse: fetchResponse,
+					requestOptions: options,
+					getHeader(name: string) {
+						return fetchResponse.headers.get(name.toLowerCase());
+					}
+				});
+			}, reject);
+		}, reject);
+
+		if (options.timeout > 0 && options.timeout !== Infinity) {
+			timeout = ((): Handle => {
+				const timer = setTimeout(function (): void {
+					const error = new RequestTimeoutError(`Request timed out after ${options.timeout}ms`);
+					reject(error);
+				}, options.timeout);
+
+				return createHandle((): void => {
+					clearTimeout(timer);
+				});
+			})();
+		}
+	});
+}

src/request/has.ts

@@ -3,4 +3,6 @@ import global from '../global';
 
 add('node-buffer', 'Buffer' in global && typeof global.Buffer === 'function');
 
+add('fetch', 'fetch' in global && typeof global.fetch === 'function');
+
 export default has;

tests/unit/request/all.ts

@@ -1,2 +1,3 @@
 import './has';
 import 'intern/dojo/has!host-node?./node:./xhr';
+import './fetch';