es6/observable/FromEventObservable.js

import { Observable } from '../Observable';
import { tryCatch } from '../util/tryCatch';
import { isFunction } from '../util/isFunction';
import { errorObject } from '../util/errorObject';
import { Subscription } from '../Subscription';
const toString = Object.prototype.toString;
function isNodeStyleEventEmitter(sourceObj) {
    return !!sourceObj && typeof sourceObj.addListener === 'function' && typeof sourceObj.removeListener === 'function';
}
function isJQueryStyleEventEmitter(sourceObj) {
    return !!sourceObj && typeof sourceObj.on === 'function' && typeof sourceObj.off === 'function';
}
function isNodeList(sourceObj) {
    return !!sourceObj && toString.call(sourceObj) === '[object NodeList]';
}
function isHTMLCollection(sourceObj) {
    return !!sourceObj && toString.call(sourceObj) === '[object HTMLCollection]';
}
function isEventTarget(sourceObj) {
    return !!sourceObj && typeof sourceObj.addEventListener === 'function' && typeof sourceObj.removeEventListener === 'function';
}
/**
 * We need this JSDoc comment for affecting ESDoc.
 * @extends {Ignored}
 * @hide true
 */
export class FromEventObservable extends Observable {
    constructor(sourceObj, eventName, selector, options) {
        super();
        this.sourceObj = sourceObj;
        this.eventName = eventName;
        this.selector = selector;
        this.options = options;
    }
    /* tslint:enable:max-line-length */
    /**
     * Creates an Observable that emits events of a specific type coming from the
     * given event target.
     *
     * <span class="informal">Creates an Observable from DOM events, or Node.js
     * EventEmitter events or others.</span>
     *
     * <img src="./img/fromEvent.png" width="100%">
     *
     * `fromEvent` accepts as a first argument event target, which is an object with methods
     * for registering event handler functions. As a second argument it takes string that indicates
     * type of event we want to listen for. `fromEvent` supports selected types of event targets,
     * which are described in detail below. If your event target does not match any of the ones listed,
     * you should use {@link fromEventPattern}, which can be used on arbitrary APIs.
     * When it comes to APIs supported by `fromEvent`, their methods for adding and removing event
     * handler functions have different names, but they all accept a string describing event type
     * and function itself, which will be called whenever said event happens.
     *
     * Every time resulting Observable is subscribed, event handler function will be registered
     * to event target on given event type. When that event fires, value
     * passed as a first argument to registered function will be emitted by output Observable.
     * When Observable is unsubscribed, function will be unregistered from event target.
     *
     * Note that if event target calls registered function with more than one argument, second
     * and following arguments will not appear in resulting stream. In order to get access to them,
     * you can pass to `fromEvent` optional project function, which will be called with all arguments
     * passed to event handler. Output Observable will then emit value returned by project function,
     * instead of the usual value.
     *
     * Remember that event targets listed below are checked via duck typing. It means that
     * no matter what kind of object you have and no matter what environment you work in,
     * you can safely use `fromEvent` on that object if it exposes described methods (provided
     * of course they behave as was described above). So for example if Node.js library exposes
     * event target which has the same method names as DOM EventTarget, `fromEvent` is still
     * a good choice.
     *
     * If the API you use is more callback then event handler oriented (subscribed
     * callback function fires only once and thus there is no need to manually
     * unregister it), you should use {@link bindCallback} or {@link bindNodeCallback}
     * instead.
     *
     * `fromEvent` supports following types of event targets:
     *
     * **DOM EventTarget**
     *
     * This is an object with `addEventListener` and `removeEventListener` methods.
     *
     * In the browser, `addEventListener` accepts - apart from event type string and event
     * handler function arguments - optional third parameter, which is either an object or boolean,
     * both used for additional configuration how and when passed function will be called. When
     * `fromEvent` is used with event target of that type, you can provide this values
     * as third parameter as well.
     *
     * **Node.js EventEmitter**
     *
     * An object with `addListener` and `removeListener` methods.
     *
     * **JQuery-style event target**
     *
     * An object with `on` and `off` methods
     *
     * **DOM NodeList**
     *
     * List of DOM Nodes, returned for example by `document.querySelectorAll` or `Node.childNodes`.
     *
     * Although this collection is not event target in itself, `fromEvent` will iterate over all Nodes
     * it contains and install event handler function in every of them. When returned Observable
     * is unsubscribed, function will be removed from all Nodes.
     *
     * **DOM HtmlCollection**
     *
     * Just as in case of NodeList it is a collection of DOM nodes. Here as well event handler function is
     * installed and removed in each of elements.
     *
     *
     * @example <caption>Emits clicks happening on the DOM document</caption>
     * var clicks = Rx.Observable.fromEvent(document, 'click');
     * clicks.subscribe(x => console.log(x));
     *
     * // Results in:
     * // MouseEvent object logged to console every time a click
     * // occurs on the document.
     *
     *
     * @example <caption>Use addEventListener with capture option</caption>
     * var clicksInDocument = Rx.Observable.fromEvent(document, 'click', true); // note optional configuration parameter
     *                                                                          // which will be passed to addEventListener
     * var clicksInDiv = Rx.Observable.fromEvent(someDivInDocument, 'click');
     *
     * clicksInDocument.subscribe(() => console.log('document'));
     * clicksInDiv.subscribe(() => console.log('div'));
     *
     * // By default events bubble UP in DOM tree, so normally
     * // when we would click on div in document
     * // "div" would be logged first and then "document".
     * // Since we specified optional `capture` option, document
     * // will catch event when it goes DOWN DOM tree, so console
     * // will log "document" and then "div".
     *
     * @see {@link bindCallback}
     * @see {@link bindNodeCallback}
     * @see {@link fromEventPattern}
     *
     * @param {EventTargetLike} target The DOM EventTarget, Node.js
     * EventEmitter, JQuery-like event target, NodeList or HTMLCollection to attach the event handler to.
     * @param {string} eventName The event name of interest, being emitted by the
     * `target`.
     * @param {EventListenerOptions} [options] Options to pass through to addEventListener
     * @param {SelectorMethodSignature<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
     */
    static create(target, eventName, options, selector) {
        if (isFunction(options)) {
            selector = options;
            options = undefined;
        }
        return new FromEventObservable(target, eventName, selector, options);
    }
    static setupSubscription(sourceObj, eventName, handler, subscriber, options) {
        let unsubscribe;
        if (isNodeList(sourceObj) || isHTMLCollection(sourceObj)) {
            for (let i = 0, len = sourceObj.length; i < len; i++) {
                FromEventObservable.setupSubscription(sourceObj[i], eventName, handler, subscriber, options);
            }
        }
        else if (isEventTarget(sourceObj)) {
            const source = sourceObj;
            sourceObj.addEventListener(eventName, handler, options);
            unsubscribe = () => source.removeEventListener(eventName, handler);
        }
        else if (isJQueryStyleEventEmitter(sourceObj)) {
            const source = sourceObj;
            sourceObj.on(eventName, handler);
            unsubscribe = () => source.off(eventName, handler);
        }
        else if (isNodeStyleEventEmitter(sourceObj)) {
            const source = sourceObj;
            sourceObj.addListener(eventName, handler);
            unsubscribe = () => source.removeListener(eventName, handler);
        }
        else {
            throw new TypeError('Invalid event target');
        }
        subscriber.add(new Subscription(unsubscribe));
    }
    _subscribe(subscriber) {
        const sourceObj = this.sourceObj;
        const eventName = this.eventName;
        const options = this.options;
        const selector = this.selector;
        let handler = selector ? (...args) => {
            let result = tryCatch(selector)(...args);
            if (result === errorObject) {
                subscriber.error(errorObject.e);
            }
            else {
                subscriber.next(result);
            }
        } : (e) => subscriber.next(e);
        FromEventObservable.setupSubscription(sourceObj, eventName, handler, subscriber, options);
    }
}
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