a class method for aggregating promises

process.Promise.join.js

process.Promise.prototype.combine = function() {
  var args = Array.prototype.slice.call( arguments ),
      count = args.length,
      results = new Array( count ),
      index = 0,
      self = this;
      
  if ( count == 1 && args[0] instanceof Array )
    return arguments.callee.apply( self, args[0] );
    
  args.forEach( function( promise ) {
    var thisIndex = index++;
    promise.addErrback( function() {
      results[ thisIndex ] = arguments;
      self.emitError.apply( self, results )
    });
 
    promise.addCallback( function() {
      results[ thisIndex ] = arguments;
      if ( !--count )
        self.emitSuccess.apply( self, results );
    });
  });
  
  return self;
}

process.Promise.join.test.js

// this example loads and compiles two external scripts,
// and fires a single event once both are loaded.

var path = module.filename.replace( /[^\/]+$/, "" ),
    dependencies = [ "sha1.js", "base64.js" ],
    promises = dependencies
      .map( function( file ) { return path + file } )
      .map( require( "posix" ).cat );

(new process.Promise).combine( promises ).addCallback( function() {
  for ( var i = 0, len = arguments.length; i < len; i++ )
    process.compile( arguments[ i ][ 0 ], dependencies[ i ] );

  // now you can call any functions in the scripts
})