too long

I am trying to excel(.xls) file upload with krajee bootstrap file upload but it seems only accept image files.

Here is My Javascript Codes:

            $("#dosyalar").fileinput({
                    uploadUrl: "ajax/upload_files.php",
                    uploadAsync: true,
                    previewFileType:'any',
                    language:"tr",
                    uploadExtraData: function() {
                        return { donem: $('#donem').val() };
                    }
                }).on('filebatchuploaderror', function(event, data, previewId, index) {
                    var form = data.form,
                        files = data.files,
                        extra = data.extra,
                        response = data.response,
                        reader = data.reader;
                    console.log(response);

            }).on('filebatchuploadsuccess', function(event, data, previewId, index) {
                    var form = data.form,
                        files = data.files,
                        extra = data.extra,
                        response = data.response,
                        reader = data.reader;
                    alert (extra.bdInteli + " " +  response.uploaded);
                    console.log(response);
            });

Here PHP Codes For Test:

// upload.php
// 'images' refers to your file input name attribute
if (empty($_FILES['dosyalar'])) {
    echo json_encode(['error'=>'No files found for upload.']);
    // or you can throw an exception
    return; // terminate
}

When try to upload batch excel files every time it says No files found for upload.It seems doesnt accept .xls extension.

How can I upload excel files using with this plugin?

Thanks

Did you specify extension ? allowedFileExtensions : ['jpg', 'png','gif', 'xlsx']