$(document).ready(function () {
    $("#checkAll").click(function () {
        var checkedStatus = this.checked;
        $("input[class=checkAllChild]").each(function () {
            this.checked = checkedStatus;
        });
    });

    $("#uploadSendButton").click(function () {
        if ($("input[class='checkAllChild']:checked").length > 0) {
            return true;
        }
        else {
            alert("You must select an email address");
            return false;
        }
    });
});