Mediator Mixin

mediator.js

var Mediator = {
  channels: {},
  
  subscribe: function( channel, fn, ctx ){
    var channels = this.channels;
    
    if ( !channels[ channel ] ){ channels[ channel ] = []; }
    
    channels[ channel ].push({ context: ctx || this, callback: fn });
    
    return this;
  },
  
  unsubscribe: function( channel, fn ){
    var channels = this.channels,
        sub;
    
    if ( !channels[ channel ] ){ return false; }
    
    for ( var i = 0, len = channels[ channel ].length; i < len; i++ ){
      sub = channels[ channel ][ i ];
      
      if ( sub.callback === fn ){
        channels[ channel ].splice(i, 1);
        
        if ( channels[ channel].length < 1 ){
          delete channels[ channel ];
        }
      }
    }
    
    return this;
  },
  
  publish: function( channel ){
    var channels = this.channels,
        args = Array.prototype.slice.call( arguments, 1 ),
        sub;
    
    if ( !channels[ channel ] ){ return false; }
    
    for ( var i = 0, len = channels[ channel ].length; i < len; i++ ){
      sub = channels[ channel ][ i ];
      sub.callback.apply( sub.context, args );
    }
    
    return this;
  }
};