函数完成之前返回的函数结果？

Question

从Firebase数据库获取一些数据并将其返回到页面上时，我遇到了一个问题。

这是数据检索功能：

let appData = function() {

    let read = async function (dataset) {
            let dataReference;
            dataReference = firebase.database().ref(dataset + '/');

            let itemDataArray = [];

            dataReference.orderByChild('created').limitToLast(100).on('value', function (response) {
                response.forEach(function (element) {
                    let itemData = element.val();

                    if (dataset == 'blog') {
                        itemDataArray.push({
                            id: element.key,
                            author: itemData.author,
                            content: itemData.content,
                            created: itemData.created,
                            target: itemData.target || '_top',
                            title: itemData.title,
                            url: itemData.url
                        });
                    }
                    else if (dataset == 'pages')
                    {
                        itemDataArray.push({
                            id: element.key,
                            content: itemData.content,
                            created: itemData.created,
                            deprecated: itemData.deprecated || false,
                            menuText: itemData.menuText,
                            modified: itemData.modified,
                            parent: itemData.parent,
                            path: itemData.path || '/',
                            repo: itemData.repo,
                            sortOrder: itemData.sortOrder || 0,
                            target: itemData.target || '_top',
                            title: itemData.title,
                            tooltip: itemData.tooltip
                        });
                    }

                });
            });

            return await itemDataArray.reverse();
        }

    return {
        read: read
    }

}();

这是我的调用函数（带有失败原因的注释）：

function renderBlog() {
    appData.read('blog').then(function(result) {
        console.log(result); // This writes a value...
        let i = 0;
        $.each(result, function( key, value ){
            console.log(result[i].created); // Nothing ever happens here...
            i++;
        });
        document.getElementById('Content').innerHTML = 'Done...';
    });
}