cast emitter as promise

gistfile1.js

Promise.castEmitter = function (item, resolveEvents, rejectEvents) {
        var methods = {
            on: _.has(item, 'on') ? 'on' : 'bind',
            off: _.has(item, 'off') ? 'off' : _.has(item, 'removeListener') ? 'removeListener' : 'unbind'
        };

        function unbindAll(events, fn) {
            for (var i = 0; i < events.length; i++)
                item[methods.off](events[i], fn);
        }

        resolveEvents = resolveEvents.trim().split(' ');
        rejectEvents = rejectEvents.trim().split(' ');

        return new Promise(function (resolve, reject) {
            _.each(resolveEvents, function (evt) { item[methods.on](evt, resolveHandler); });
            _.each(rejectEvents, function (evt) { item[methods.on](evt, rejectHandler); });

            function resolveHandler() {
                resolve(_.toArray(arguments));
                unbindAll(rejectEvents, rejectHandler);
            }
            function rejectHandler() {
                reject(_.toArray(arguments));
                unbindAll(resolveEvents, resolveHandler);
            }
        }); 
    };