Promises + Generators

asyncGenerator.js

function async(generatorFn) {
    return function () {
        var iterator = generatorFn.apply(this, arguments);
        
        function handle(result) {
            if (result.done) return Promise.resolve(result.value);
            
            return Promise.resolve(result.value).then(function (res) {
                return handle(iterator.next(res));
            }, function (err) {
                return handle(iterator.throw(err));
            });
        }
        
        try {
            return handle(iterator.next());
        } catch (ex) {
            return Promise.reject(ex);
        }
    }
}