rxjs/_esm2015/observable/FromEventObservable.js

Reactive Extensions for modern JavaScript

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
     * EventEmitter events or others.</span>
     *
     * <img src="./img/fromEvent.png" width="100%">
     *
     * Creates an Observable by attaching an event listener to an "event target",
     * which may be an object with `addEventListener` and `removeEventListener`,
     * a Node.js EventEmitter, a jQuery style EventEmitter, a NodeList from the
     * DOM, or an HTMLCollection from the DOM. The event handler is attached when
     * the output Observable is subscribed, and removed when the Subscription is
     * unsubscribed.
     *
     * @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 everytime a click
     * // occurs on the document.
     *
     * @see {@link from}
     * @see {@link fromEventPattern}
     *
     * @param {EventTargetLike} target The DOMElement, event target, Node.js
     * EventEmitter, 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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