cjs-emitter

Basic events emitter implementation

Almost all components in STB SDK emit events: a Model emits an event each time an attribute is set, a router emits an event when a page is opened. All components which emit events are instances of Emitter.

Typically, there aren't any strict restrictions on event names, as any string will be accepted. Usually it's a lowercase string with no spaces. Possible values: click, move, focus:item.

Functions can then be attached to objects, to be executed when an event is emitted. These functions are called listeners. Inside a listener function, this refers to the Emitter that the listener was attached to.

Installation

npm install cjs-emitter

Usage

Add the constructor to the scope:

var Emitter = require('cjs-emitter');

Create an instance:

var emitter = new Emitter();

Add listeners for some events:

emitter.addListener('click', function ( data ) { ... });
emitter.addListener('click', function ( data ) { ... });

Add listener that will be notified only one time:

emitter.once('click', function ( data ) { ... });

Add multiple listeners at once:

emitter.addListeners({
    click: function ( data ) {},
    close: function ( data ) {}
});

Remove all instances of the given callback:

emitter.removeListener('click', func1);

Remove all callbacks for the given event name:

emitter.removeListener('click');

Clears all events:

emitter.removeListener();

Execute each of the listeners in the given order with the supplied arguments:

emitter.emit('init');
emitter.emit('click', {src: panel1, dst: panel2});
emitter.emit('load', error, data);

Performance notes

It's a good idea to emit event only when there are some listeners:

if ( emitter.events['click'] ) {
	// notify listeners
    emitter.emit('click', {event: event});
}

Debug mode

There is a global var DEBUG which activates additional consistency checks and protection logic not available in release mode.

Contribution

If you have any problem or suggestion please open an issue here. Pull requests are welcomed with respect to the JavaScript Code Style.

License

cjs-emitter is released under the GPL-3.0 License.