refactor(TimeoutError): timeout throws typed TimeoutError

closes #1997

spec/operators/timeout-spec.ts

@@ -6,7 +6,7 @@ const Observable = Rx.Observable;
 
 /** @test {timeout} */
 describe('Observable.prototype.timeout', () => {
- const defaultTimeoutError = new Error('timeout');
+ const defaultTimeoutError = new Rx.TimeoutError();
 
  asDiagram('timeout(50)')('should timeout after a specified timeout period', () => {
  const e1 = cold('-------a--b--|');

src/Rx.ts

@@ -155,6 +155,7 @@ export {Notification} from './Notification';
 export {EmptyError} from './util/EmptyError';
 export {ArgumentOutOfRangeError} from './util/ArgumentOutOfRangeError';
 export {ObjectUnsubscribedError} from './util/ObjectUnsubscribedError';
+export {TimeoutError} from './util/TimeoutError';
 export {UnsubscriptionError} from './util/UnsubscriptionError';
 export {TimeInterval} from './operator/timeInterval';
 export {Timestamp} from './operator/timestamp';

src/operator/timeout.ts

@@ -5,6 +5,7 @@ import { Subscriber } from '../Subscriber';
 import { Scheduler } from '../Scheduler';
 import { Observable } from '../Observable';
 import { TeardownLogic } from '../Subscription';
+import { TimeoutError } from '../util/TimeoutError';
 
 /**
  * @param due
@@ -80,25 +81,25 @@ class TimeoutSubscriber<T> extends Subscriber<T> {
  this._previousIndex = currentIndex;
  }
 
- protected _next(value: T) {
+ protected _next(value: T): void {
  this.destination.next(value);
 
  if (!this.absoluteTimeout) {
  this.scheduleTimeout();
  }
  }
 
- protected _error(err: any) {
+ protected _error(err: any): void {
  this.destination.error(err);
  this._hasCompleted = true;
  }
 
- protected _complete() {
+ protected _complete(): void {
  this.destination.complete();
  this._hasCompleted = true;
  }
 
- notifyTimeout() {
- this.error(this.errorToSend || new Error('timeout'));
+ notifyTimeout(): void {
+ this.error(this.errorToSend || new TimeoutError());
  }
 }

src/util/TimeoutError.ts

@@ -0,0 +1,15 @@
+/**
+ * An error thrown when duetime elapses.
+ *
+ * @see {@link timeout}
+ *
+ * @class TimeoutError
+ */
+export class TimeoutError extends Error {
+ constructor() {
+ const err: any = super('Timeout has occurred');
+ (<any> this).name = err.name = 'TimeoutError';
+ (<any> this).stack = err.stack;
+ (<any> this).message = err.message;
+ }
+}