bd-core/src/eventHub.js

a JavaScript library for building browser-hosted user interfaces

import {Destroyable} from './Destroyable.js';
import {STAR} from './symbols.js';

const listenerCatalog = new WeakMap();

function eventHub(superClass) {
    return class extends (superClass || class {
    }) {
        // protected interface...
        bdNotify(e) {
            const events = listenerCatalog.get(this);
            if (!events) {
                return;
            }

            let handlers;
            if (e instanceof Event) {
                handlers = events[e.type];
            } else {
                // eslint-disable-next-line no-lonely-if
                if (e.type) {
                    handlers = events[e.type];
                    e.target = this;
                } else if (!e.name) {
                    handlers = events[e];
                    e = {type: e, name: e, target: this};
                } else {
                    // eslint-disable-next-line no-console
                    console.warn('event.name is deprecated; use event.type');
                    handlers = events[e.name];
                    e.type = e.name;
                    e.target = this;
                }
            }

            if (handlers) {
                handlers.slice().forEach(theDestroyable => theDestroyable.proc(e));
            }
            if ((handlers = events[STAR])) {
                handlers.slice().forEach(theDestroyable => theDestroyable.proc(e));
            }
        }

        // public interface...
        get isBdEventHub() {
            return true;
        }

        advise(eventName, handler) {
            if (!handler) {
                const hash = eventName;
                return Reflect.ownKeys(hash).map(key => this.advise(key, hash[key]));
            } else if (Array.isArray(eventName)) {
                return eventName.map(name => this.advise(name, handler));
            } else {
                let events = listenerCatalog.get(this);
                if (!events) {
                    listenerCatalog.set(this, (events = {}));
                }
                const result = new Destroyable(handler, events[eventName] || (events[eventName] = []));
                this.own && this.own(result);
                return result;
            }
        }

        destroyAdvise(eventName) {
            const events = listenerCatalog.get(this);
            if (!events) {
                return;
            }
            if (eventName) {
                const handlers = events[eventName];
                if (handlers) {
                    handlers.forEach(h => h.destroy());
                    delete events[eventName];
                }
            } else {
                // eslint-disable-next-line no-shadow
                Reflect.ownKeys(events).forEach(eventName => {
                    events[eventName].forEach(h => h.destroy());
                });
                listenerCatalog.delete(this);
            }
        }
    };
}

const EventHub = eventHub();

export {
    eventHub,
    EventHub
};