Basic events emitter implementation

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.

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 events only when there are some listeners:

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

Development mode

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

Contribution

If you have any problems or suggestions please open an issue according to the contribution rules.

License

cjs-emitter is released under the MIT License.