import { Observable } from '../Observable';
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import { isArray } from '../util/isArray';
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import { isFunction } from '../util/isFunction';
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import { Subscriber } from '../Subscriber';
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import { map } from '../operators/map';
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const toString: Function = (() => Object.prototype.toString)();
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export interface NodeStyleEventEmitter {
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addListener: (eventName: string | symbol, handler: NodeEventHandler) => this;
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removeListener: (eventName: string | symbol, handler: NodeEventHandler) => this;
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}
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export type NodeEventHandler = (...args: any[]) => void;
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// For APIs that implement `addListener` and `removeListener` methods that may
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// not use the same arguments or return EventEmitter values
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// such as React Native
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export interface NodeCompatibleEventEmitter {
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addListener: (eventName: string, handler: NodeEventHandler) => void | {};
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removeListener: (eventName: string, handler: NodeEventHandler) => void | {};
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}
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export interface JQueryStyleEventEmitter {
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on: (eventName: string, handler: Function) => void;
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off: (eventName: string, handler: Function) => void;
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}
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export interface HasEventTargetAddRemove<E> {
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addEventListener(type: string, listener: ((evt: E) => void) | null, options?: boolean | AddEventListenerOptions): void;
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removeEventListener(type: string, listener?: ((evt: E) => void) | null, options?: EventListenerOptions | boolean): void;
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}
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export type EventTargetLike<T> = HasEventTargetAddRemove<T> | NodeStyleEventEmitter | NodeCompatibleEventEmitter | JQueryStyleEventEmitter;
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export type FromEventTarget<T> = EventTargetLike<T> | ArrayLike<EventTargetLike<T>>;
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export interface EventListenerOptions {
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capture?: boolean;
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passive?: boolean;
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once?: boolean;
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}
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export interface AddEventListenerOptions extends EventListenerOptions {
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once?: boolean;
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passive?: boolean;
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}
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/* tslint:disable:max-line-length */
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export function fromEvent<T>(target: FromEventTarget<T>, eventName: string): Observable<T>;
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/** @deprecated resultSelector no longer supported, pipe to map instead */
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export function fromEvent<T>(target: FromEventTarget<T>, eventName: string, resultSelector: (...args: any[]) => T): Observable<T>;
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export function fromEvent<T>(target: FromEventTarget<T>, eventName: string, options: EventListenerOptions): Observable<T>;
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/** @deprecated resultSelector no longer supported, pipe to map instead */
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export function fromEvent<T>(target: FromEventTarget<T>, eventName: string, options: EventListenerOptions, resultSelector: (...args: any[]) => T): Observable<T>;
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/* tslint:enable:max-line-length */
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/**
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* Creates an Observable that emits events of a specific type coming from the
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* given event target.
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*
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* <span class="informal">Creates an Observable from DOM events, or Node.js
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* EventEmitter events or others.</span>
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*
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* 
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*
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* `fromEvent` accepts as a first argument event target, which is an object with methods
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* for registering event handler functions. As a second argument it takes string that indicates
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* type of event we want to listen for. `fromEvent` supports selected types of event targets,
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* which are described in detail below. If your event target does not match any of the ones listed,
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* you should use {@link fromEventPattern}, which can be used on arbitrary APIs.
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* When it comes to APIs supported by `fromEvent`, their methods for adding and removing event
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* handler functions have different names, but they all accept a string describing event type
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* and function itself, which will be called whenever said event happens.
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*
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* Every time resulting Observable is subscribed, event handler function will be registered
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* to event target on given event type. When that event fires, value
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* passed as a first argument to registered function will be emitted by output Observable.
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* When Observable is unsubscribed, function will be unregistered from event target.
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*
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* Note that if event target calls registered function with more than one argument, second
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* and following arguments will not appear in resulting stream. In order to get access to them,
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* you can pass to `fromEvent` optional project function, which will be called with all arguments
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* passed to event handler. Output Observable will then emit value returned by project function,
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* instead of the usual value.
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*
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* Remember that event targets listed below are checked via duck typing. It means that
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* no matter what kind of object you have and no matter what environment you work in,
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* you can safely use `fromEvent` on that object if it exposes described methods (provided
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* of course they behave as was described above). So for example if Node.js library exposes
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* event target which has the same method names as DOM EventTarget, `fromEvent` is still
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* a good choice.
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*
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* If the API you use is more callback then event handler oriented (subscribed
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* callback function fires only once and thus there is no need to manually
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* unregister it), you should use {@link bindCallback} or {@link bindNodeCallback}
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* instead.
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*
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* `fromEvent` supports following types of event targets:
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*
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* **DOM EventTarget**
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*
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* This is an object with `addEventListener` and `removeEventListener` methods.
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*
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* In the browser, `addEventListener` accepts - apart from event type string and event
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* handler function arguments - optional third parameter, which is either an object or boolean,
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* both used for additional configuration how and when passed function will be called. When
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* `fromEvent` is used with event target of that type, you can provide this values
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* as third parameter as well.
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*
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* **Node.js EventEmitter**
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*
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* An object with `addListener` and `removeListener` methods.
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*
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* **JQuery-style event target**
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*
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* An object with `on` and `off` methods
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*
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* **DOM NodeList**
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*
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* List of DOM Nodes, returned for example by `document.querySelectorAll` or `Node.childNodes`.
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*
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* Although this collection is not event target in itself, `fromEvent` will iterate over all Nodes
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* it contains and install event handler function in every of them. When returned Observable
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* is unsubscribed, function will be removed from all Nodes.
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*
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* **DOM HtmlCollection**
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*
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* Just as in case of NodeList it is a collection of DOM nodes. Here as well event handler function is
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* installed and removed in each of elements.
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*
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*
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* ## Examples
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* ### Emits clicks happening on the DOM document
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* ```ts
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* import { fromEvent } from 'rxjs';
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*
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* const clicks = fromEvent(document, 'click');
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* clicks.subscribe(x => console.log(x));
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*
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* // Results in:
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* // MouseEvent object logged to console every time a click
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* // occurs on the document.
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* ```
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*
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* ### Use addEventListener with capture option
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* ```ts
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* import { fromEvent } from 'rxjs';
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*
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* const clicksInDocument = fromEvent(document, 'click', true); // note optional configuration parameter
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* // which will be passed to addEventListener
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* const clicksInDiv = fromEvent(someDivInDocument, 'click');
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*
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* clicksInDocument.subscribe(() => console.log('document'));
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* clicksInDiv.subscribe(() => console.log('div'));
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*
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* // By default events bubble UP in DOM tree, so normally
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* // when we would click on div in document
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* // "div" would be logged first and then "document".
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* // Since we specified optional `capture` option, document
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* // will catch event when it goes DOWN DOM tree, so console
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* // will log "document" and then "div".
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* ```
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*
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* @see {@link bindCallback}
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* @see {@link bindNodeCallback}
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* @see {@link fromEventPattern}
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*
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* @param {FromEventTarget<T>} target The DOM EventTarget, Node.js
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* EventEmitter, JQuery-like event target, NodeList or HTMLCollection to attach the event handler to.
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* @param {string} eventName The event name of interest, being emitted by the
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* `target`.
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* @param {EventListenerOptions} [options] Options to pass through to addEventListener
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* @return {Observable<T>}
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* @name fromEvent
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*/
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export function fromEvent<T>(
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target: FromEventTarget<T>,
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eventName: string,
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options?: EventListenerOptions | ((...args: any[]) => T),
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resultSelector?: ((...args: any[]) => T)
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): Observable<T> {
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if (isFunction(options)) {
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// DEPRECATED PATH
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resultSelector = options;
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options = undefined;
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}
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if (resultSelector) {
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// DEPRECATED PATH
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return fromEvent<T>(target, eventName, <EventListenerOptions | undefined>options).pipe(
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map(args => isArray(args) ? resultSelector(...args) : resultSelector(args))
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);
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}
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return new Observable<T>(subscriber => {
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function handler(e: T) {
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if (arguments.length > 1) {
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subscriber.next(Array.prototype.slice.call(arguments));
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} else {
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subscriber.next(e);
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}
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}
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setupSubscription(target, eventName, handler, subscriber, options as EventListenerOptions);
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});
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}
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function setupSubscription<T>(sourceObj: FromEventTarget<T>, eventName: string,
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handler: (...args: any[]) => void, subscriber: Subscriber<T>,
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options?: EventListenerOptions) {
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let unsubscribe: () => void;
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if (isEventTarget(sourceObj)) {
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const source = sourceObj;
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sourceObj.addEventListener(eventName, handler, options);
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unsubscribe = () => source.removeEventListener(eventName, handler, options);
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} else if (isJQueryStyleEventEmitter(sourceObj)) {
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const source = sourceObj;
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sourceObj.on(eventName, handler);
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unsubscribe = () => source.off(eventName, handler);
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} else if (isNodeStyleEventEmitter(sourceObj)) {
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const source = sourceObj;
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sourceObj.addListener(eventName, handler as NodeEventHandler);
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unsubscribe = () => source.removeListener(eventName, handler as NodeEventHandler);
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} else if (sourceObj && (sourceObj as any).length) {
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for (let i = 0, len = (sourceObj as any).length; i < len; i++) {
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setupSubscription(sourceObj[i], eventName, handler, subscriber, options);
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}
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} else {
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throw new TypeError('Invalid event target');
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}
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subscriber.add(unsubscribe);
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}
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function isNodeStyleEventEmitter(sourceObj: any): sourceObj is NodeStyleEventEmitter {
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return sourceObj && typeof sourceObj.addListener === 'function' && typeof sourceObj.removeListener === 'function';
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}
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function isJQueryStyleEventEmitter(sourceObj: any): sourceObj is JQueryStyleEventEmitter {
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return sourceObj && typeof sourceObj.on === 'function' && typeof sourceObj.off === 'function';
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}
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function isEventTarget(sourceObj: any): sourceObj is HasEventTargetAddRemove<any> {
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return sourceObj && typeof sourceObj.addEventListener === 'function' && typeof sourceObj.removeEventListener === 'function';
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}
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