es6中的雙箭頭函數

原代碼：

const fetchPosts = subreddit => dispatch => {

dispatch(requestPosts(subreddit));

    return common.fetch({url: config.argumentSubmit, method: 'POST'})

    .then(response => response.message)

    .then(message => dispatch(receivePosts(subreddit, message)));

};

解析爲：

const fetchPosts = function (subreddit) {

return function (dispatch) {

            return  common.fetch({url: config.argumentSubmit, method: 'POST'})

                       .then(response => response.message)

                        .then(message => dispatch(receivePosts(subreddit, message)));
            }

}

雙箭頭意思是導出一個函數