example ajax upload.html

<h2>Загрузка картинки</h2>
<form method="post" action="/admin/images/upload.json" enctype="multipart/form-data" id="image-upload-form"
        data-success="/admin/images/">
    <div class="row">
        <div class="form-group col-md-6">
            <label for="image" class="control-label">картинка</label>
            <input type="file" class="form-control" id="image" name="image" required/>
        </div>
    </div>
    <button type="submit" class="btn btn-default">Сохранить</button>
</form>

<script>
    $(function () {
        var files;

        var $form = $('#image-upload-form');
        var action = $form.prop('action');
        var success = $form.data('success');

        var $input = $form.find('[type=file]').first();
        $input.change(function (e) {
            console.log(e);
            files = e.target.files;
        });

        $form.submit(function (e) {
            e.preventDefault();
            var formData = new FormData();
            $.each(files, function (key, value) {
                console.log(key, value);
                formData.append($input.prop('name'), value);
            });
            console.log(formData);
            $.ajax({
                url: action,
                type: 'POST',
                data: formData,
                dataType: 'json',
                processData: false,
                contentType: false,
                success: function (data, textStatus, jqXHR) {
                    console.log(data, textStatus, jqXHR);
                },
                error: function (jqXHR, textStatus, errorThrown) {
                    console.log(jqXHR, textStatus, errorThrown);
                }
            });
        });
    });
</script>