function ShowValidationCombinedMessageBox()
{
    var errorText = "";
    $("div[class='validationSummary'] > ul > li").each(
        function(idx, item) {
            var itemText = jQuery.trim($(item).text());
            errorText += "- " + itemText + "\r\n";
        }
    );
    if (errorText !== "")
    {
        errorText = "The form could not be submitted for the following reasons:\r\n" + errorText;
        alert(errorText);
    }
}

$(document).ready(ShowValidationCombinedMessageBox);