Typically, there are no 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.

npm install cjs-emitter

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);

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

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

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

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

cjs-emitter is released under the MIT License.