IsoldaJS PubSub

This is a stand-alone Pub/Sub implementation ported from Backbone.Events.

Can be used both in Node.js and in the browser (< 6Kb minified and gzipped).

It has the full Backbone's test suite ported as well.

The module can be mixed in to any object, giving the object the ability to bind and trigger custom named events. Events do not have to be declared before they are bound, and may take passed arguments. For example:

var _ = require('lodash');
var PubSub = require('@isoldajs/pubsub');

var object = {};

_.extend(object, PubSub);

object.on("alert", function(msg) {
  alert("Triggered " + msg);
});

object.trigger("alert", "an event");

For example, to make a handy event dispatcher that can coordinate events among different areas of your application: var dispatcher = _.clone(PubSub).

on object.on(event, callback, [context]) Alias: bind

Bind a callback function to an object. The callback will be invoked whenever the event is fired. If you have a large number of different events on a page, the convention is to use colons to namespace them: "poll:start", or "change:selection". The event string may also be a space-delimited list of several events...

book.on("change:title change:author", ...);

To supply a context value for this when the callback is invoked, pass the optional third argument: model.on('change', this.render, this).

Callbacks bound to the special "all" event will be triggered when any event occurs, and are passed the name of the event as the first argument. For example, to proxy all events from one object to another:

proxy.on("all", function(eventName) {
  object.trigger(eventName);
});

All PubSub event methods also support an event map syntax, as an alternative to positional arguments:

book.on({
  "change:title": titleView.update,
  "change:author": authorPane.update,
  "destroy": bookView.remove
});

off object.off([event], [callback], [context]) Alias: unbind

Remove a previously-bound callback function from an object. If no context is specified, all of the versions of the callback with different contexts will be removed. If no callback is specified, all callbacks for the event will be removed. If no event is specified, callbacks for all events will be removed.

// Removes just the `onChange` callback.
object.off("change", onChange);

// Removes all "change" callbacks.
object.off("change");

// Removes the `onChange` callback for all events.
object.off(null, onChange);

// Removes all callbacks for `context` for all events.
object.off(null, null, context);

// Removes all callbacks on `object`.
object.off();

Note that calling off will indeed remove all events on the object — including events that other libraries may use for internal bookkeeping.

trigger object.trigger(event, [*args])

Trigger callbacks for the given event, or space-delimited list of events. Subsequent arguments to trigger will be passed along to the event callbacks.

once object.once(event, callback, [context])

Just like on, but causes the bound callback to fire only once before being removed. Handy for saying "the next time that X happens, do this". When multiple events are passed in using the space separated syntax, the event will fire once for every event you passed in, not once for a combination of all events

listenTo object.listenTo(other, event, callback)

Tell an object to listen to a particular event on an other object. The advantage of using this form, instead of other.on(event, callback, object), is that listenTo allows the object to keep track of the events, and they can be removed all at once later on. The callback will always be called with object as context.

view.listenTo(model, 'change', view.render);

stopListening object.stopListening([other], [event], [callback])

Tell an object to stop listening to events. Either call stopListening with no arguments to have the object remove all of its registered callbacks ... or be more precise by telling it to remove just the events it's listening to on a specific object, or a specific event, or just a specific callback.

view.stopListening();

view.stopListening(model);

listenToOnce object.listenToOnce(other, event, callback)

Just like listenTo, but causes the bound callback to fire only once before being removed.