Uploading files to server with queues

queued-upload-requests.js

/*
 * Загружает файл на сервер
 */

var requestQueue = [],
    sendingRequest = false;

window.attachRequestToQueue = (queue) => {
    requestQueue.push(queue);
    doRequestQueue();
};

window.doRequestQueue = () => {
    if (!sendingRequest && requestQueue.length > 0) {
        var queue = requestQueue.shift();
        queue().always(function () {
            sendingRequest = false;
            doRequestQueue();
        });
        sendingRequest = true;
    }
};

window.uploadImageFile = (file, callback) => {

    var url = window.Laravel.uploadImageUrl;

    var data = new FormData();
    data.append('photo', file);

    var action = (data64) => {
        var progress = [
            '<div>Идёт загрузка изображения</div>',
            '<div class="progress progress-striped active" style="margin-top: 5px">',
            '   <div class="progress-bar progress-bar-warning" role="progressbar" aria-valuenow="60" aria-valuemin="0" aria-valuemax="100" style="width: 100%"></div>',
            '</div>'
        ].join('');

        var text = [
            '<div class="row">',
            '   <div class="col-md-3"><img class="img-responsive img-thumbnail" src="' + data64 + '"></div>',
            '   <div class="col-md-9">' + progress + '</div>',
            '</div>'
        ].join('');

        var queue = () => {
            var uploadNotify;

            var request = $.ajax({
                url: url,
                method: 'POST',
                data: data,
                success: callback,
                beforeSend: function () {
                    uploadNotify = new PNotify({
                        title: 'Загрузка изображения',
                        text: text,
                        type: 'info',
                        nonblock: {
                            nonblock: true
                        },
                        styling: 'bootstrap3'
                    });
                },
                complete: function () {
                    uploadNotify.remove();
                },
                error: function (xhr) {
                    new PNotify({
                        text: 'Ошибка загрузки файла',
                        type: 'error',
                        styling: 'bootstrap3'
                    });
                },
                contentType: false,
                processData: false,
            });

            return request;
        };

        attachRequestToQueue(queue);
    };

    var reader = new FileReader();
    reader.addEventListener('load', function (e) {
        action(e.target.result);
    }.bind(this));
    reader.readAsDataURL(file);

};