feat: Data URI support (node-fetch#659)

Adds support for Data URIs using native methods in Node 5.10.0+

Author: Richienb

src/index.js

@@ -38,6 +38,17 @@ export default function fetch(url, opts) {
 		throw new Error('native promise missing, set fetch.Promise to your favorite alternative');
 	}
 
+	if (/^data:/.test(url)) {
+		const request = new Request(url, opts);
+		try {
+			const data = Buffer.from(url.split(',')[1], 'base64')
+			const res = new Response(data.body, { headers: { 'Content-Type': data.mimeType || url.match(/^data:(.+);base64,.*$/)[1] } });
+			return fetch.Promise.resolve(res);
+		} catch (err) {
+			return fetch.Promise.reject(new FetchError(`[${request.method}] ${request.url} invalid URL, ${err.message}`, 'system', err));
+		}
+	}
+
 	Body.Promise = fetch.Promise;
 
 	// wrap http.request into fetch

test/test.js

@@ -2834,4 +2834,29 @@ describe('external encoding', () => {
 			});
 		});
 	});
+
+	describe('data uri', function() {
+		const dataUrl = 'data:image/gif;base64,R0lGODlhAQABAIAAAAUEBAAAACwAAAAAAQABAAACAkQBADs=';
+
+		const invalidDataUrl = 'data:@@@@';
+
+		it('should accept data uri', function() {
+			return fetch(dataUrl).then(r => {
+				console.assert(r.status == 200);
+				console.assert(r.headers.get('Content-Type') == 'image/gif');
+
+				return r.buffer().then(b => {
+					console.assert(b instanceof Buffer);
+				});
+			});
+		});
+
+		it('should reject invalid data uri', function() {
+			return fetch(invalidDataUrl)
+			.catch(e => {
+				console.assert(e);
+				console.assert(e.message.includes('invalid URL'));
+			});
+		});
+	});
 });