feat(fromEvent): will now emit an array when event emits multiple arguments

If an event has a callback with multiple arguments, they will be emitted as an array

Author: benlesh

spec/observables/fromEvent-spec.ts

@@ -178,6 +178,29 @@ describe('fromEvent', () => {
     send('test');
   });
 
+  it('should emit multiple arguments from event as an array', (done: MochaDone) => {
+    let send;
+    const obj = {
+      on: (name: string, handler: Function) => {
+        send = handler;
+      },
+      off: () => {
+        //noop
+      }
+    };
+
+    fromEvent(obj, 'click').take(1)
+      .subscribe((e: any) => {
+        expect(e).to.deep.equal([1, 2, 3]);
+      }, (err: any) => {
+        done(new Error('should not be called'));
+      }, () => {
+        done();
+      });
+
+    send(1, 2, 3);
+  });
+
   it('should not throw an exception calling toString on obj with a null prototype', (done: MochaDone) => {
     // NOTE: Can not test with Object.create(null) or `class Foo extends null`
     // due to TypeScript bug. https://github.com/Microsoft/TypeScript/issues/1108

src/internal/observable/fromEvent.ts

@@ -144,7 +144,13 @@ export function fromEvent<T>(
 ): Observable<T> {
 
   return new Observable<T>(subscriber => {
-    const handler = (e: T) => subscriber.next(e);
+    function handler(e: T) {
+      if (arguments.length > 1) {
+        subscriber.next(Array.prototype.slice.call(arguments));
+      } else {
+        subscriber.next(e);
+      }
+    }
     setupSubscription(target, eventName, handler, subscriber, options as EventListenerOptions);
   });
 }