feat(fromEvent): remove resultSelector

- removes resultSelector from function signature to simplify the API

BREAKING CHANGE: result selector removed, use `map` instead: `fromEvent(target, 'click', fn)` becomes `fromEvent(target, 'click').pipe(map(fn))`

Author: benlesh

spec/observables/fromEvent-spec.ts

@@ -178,114 +178,6 @@ describe('fromEvent', () => {
     send('test');
   });
 
-  it('should pass through events that occur and use the selector if provided', (done: MochaDone) => {
-    let send;
-    const obj = {
-      on: (name: string, handler: Function) => {
-        send = handler;
-      },
-      off: () => {
-        //noop
-      }
-    };
-
-    function selector(x) {
-      return x + '!';
-    }
-
-    fromEvent(obj, 'click', selector).take(1)
-      .subscribe((e: any) => {
-        expect(e).to.equal('test!');
-      }, (err: any) => {
-        done(new Error('should not be called'));
-      }, () => {
-        done();
-      });
-
-    send('test');
-  });
-
-  it('should not fail if no event arguments are passed and the selector does not return', (done: MochaDone) => {
-    let send;
-    const obj = {
-      on: (name: string, handler: Function) => {
-        send = handler;
-      },
-      off: () => {
-        //noop
-      }
-    };
-
-    function selector() {
-      //noop
-    }
-
-    fromEvent(obj, 'click', selector).take(1)
-      .subscribe((e: any) => {
-        expect(e).not.exist;
-      }, (err: any) => {
-        done(new Error('should not be called'));
-      }, () => {
-        done();
-      });
-
-    send();
-  });
-
-  it('should return a value from the selector if no event arguments are passed', (done: MochaDone) => {
-    let send;
-    const obj = {
-      on: (name: string, handler: Function) => {
-        send = handler;
-      },
-      off: () => {
-        //noop
-      }
-    };
-
-    function selector() {
-      return 'no arguments';
-    }
-
-    fromEvent(obj, 'click', selector).take(1)
-      .subscribe((e: any) => {
-        expect(e).to.equal('no arguments');
-      }, (err: any) => {
-        done(new Error('should not be called'));
-      }, () => {
-        done();
-      });
-
-    send();
-  });
-
-  it('should pass multiple arguments to selector from event emitter', (done: MochaDone) => {
-    let send;
-    const obj = {
-      on: (name: string, handler: Function) => {
-        send = handler;
-      },
-      off: () => {
-        //noop
-      }
-    };
-
-    function selector(x, y, z) {
-      return [].slice.call(arguments);
-    }
-
-    fromEvent(obj, 'click', selector).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

@@ -22,9 +22,8 @@ export type EventListenerOptions = {
 
 /* tslint:disable:max-line-length */
 export function fromEvent<T>(target: EventTargetLike, eventName: string): Observable<T>;
-export function fromEvent<T>(target: EventTargetLike, eventName: string, selector: (...args: any[]) => T): Observable<T>;
+export function fromEvent<T>(target: EventTargetLike, eventName: string): Observable<T>;
 export function fromEvent<T>(target: EventTargetLike, eventName: string, options: EventListenerOptions): Observable<T>;
-export function fromEvent<T>(target: EventTargetLike, eventName: string, options: EventListenerOptions, selector: (...args: any[]) => T): Observable<T>;
 /* tslint:enable:max-line-length */
 
 /**
@@ -135,35 +134,17 @@ export function fromEvent<T>(target: EventTargetLike, eventName: string, options
  * @param {string} eventName The event name of interest, being emitted by the
  * `target`.
  * @param {EventListenerOptions} [options] Options to pass through to addEventListener
- * @param {(...args: any[]) => T} [selector] An optional function to
- * post-process results. It takes the arguments from the event handler and
- * should return a single value.
  * @return {Observable<T>}
- * @static true
  * @name fromEvent
- * @owner Observable
  */
-export function fromEvent<T>(target: EventTargetLike,
-                             eventName: string,
-                             options?: EventListenerOptions | ((...args: any[]) => T),
-                             selector?: (...args: any[]) => T): Observable<T> {
-  if (isFunction(options)) {
-    selector = options as ((...args: any[]) => T);
-    options = undefined;
-  }
+export function fromEvent<T>(
+  target: EventTargetLike,
+  eventName: string,
+  options?: EventListenerOptions
+): Observable<T> {
 
   return new Observable<T>(subscriber => {
-    const handler = selector ? (...args: any[]) => {
-      let result: any;
-      try {
-        result = selector(...args);
-      } catch (err) {
-        subscriber.error(err);
-        return;
-      }
-      subscriber.next(result);
-    } : (e: any) => subscriber.next(e);
-
+    const handler = (e: T) => subscriber.next(e);
     setupSubscription(target, eventName, handler, subscriber, options as EventListenerOptions);
   });
 }