event-dispatcher

Event Dispatcher

Alongside standard event emitting mechanism, this library provides some additional utilities like event aggregator and generic event dispatching repository.

This is an AMD library. To use it with Node.js and other CommonJS modules based environments I recommend jsloader/jsloader.

This library is partially modeled after symfony/EventDispatcher.

Examples

Basic usage

Dispatching events

require([
    "Bender/EventDispatcher/Event",
    "Bender/EventDispatcher/EventDispatcher"
], function (Event, EventDispatcher) {
    var eventDispatcher = new EventDispatcher();

    eventDispatcher.getSupportedEvents = function () {
        return ["a"];
    };

    eventDispatcher.addListener("a", function (evt) {
        console.log("hello %s!", evt.data.place); // hello world
    });

    eventDispatcher.dispatch("a", new Event({ place: "world" }));
});

Aggregating event dispatchers

var auto = require("jsloader"),
    eventAggregator,
    eventDispatcherA,
    eventDispatcherB,
    Event = auto.load("Bender/EventDispatcher/Event"),
    EventAggregator = auto.load("Bender/EventDispatcher/EventAggregator"),
    EventDispatcher = auto.load("Bender/EventDispatcher/EventDispatcher");

eventAggregator = new EventAggregator();

eventDispatcherA.getSupportedEvents = function () {
    return ["a"];
};

eventDispatcherB.getSupportedEvents = function () {
    return ["b"];
};

eventAggregator.add(eventDispatcherA);
eventAggregator.add(eventDispatcherB);

eventAggregator.addListener("a", function (evt) {
    console.log("hello %s!", evt.data.place); // hello world
});

eventAggregator.addListener("b", function (evt) {
    console.log("hello %s!", evt.data.place); // hello planet
});

eventDispatcherA.dispatch("a", new Event({ place: "world" }));
eventDispatcherB.dispatch("b", new Event({ place: "planet" }));

Advanced usage

Exposing single module entry point using two combined modules

// module/a.js

var eventAggregator,
    eventDispatcherAB = require("foo").eventDispatcherAB,
    eventDispatcherC = require("bar").eventDispatcherC;

eventAggregator = new EventAggregator();

eventAggregator.add(eventDispatcherAB);
eventAggregator.add(eventDispatcherC);

module.exports = eventAggregator;

// module/b.js

var a = require("a");

// eventDispatcherAB is going to handle this
a.addListener("a", function () {});

// eventDispatcherAB is going to handle this
a.addListener("b", function () {});

// eventDispatcherC is going to handle this
a.addListener("c", function () {});

Generic repository based on event dispatcher

define(["Bender/EventDispatcher/EventDispatcher/Repository"], function (Repository) {
    var repository = new Repository();

    repository.addListener(Repository.EVENT_ITEM_ADDED, function (evt) {
        var item = evt.data.item,
            repository = evt.data.repository;

        console.log("added: " + item);

        if (("world" === item) && 2148 !== (new Date().getFullYear())) {
            // this one should not be here for some reason
            repository.remove(item);
        }
    });

    repository.addListener(Repository.EVENT_ITEM_REMOVED, function (evt) {
        console.log("removed: " + evt.data.item);
    });

    repository.add("hello"); // added: hello
    repository.add("world"); // added: world, removed: world
});

Semantic Versioning

This repository follows Semantic Versioning convention.