function DataChanged() {
    $("#isNeedToSave").val("1");
}

function isNeedSave() {
    if (form_is_modified(document.forms[0]) || $("#isNeedToSave").val() == "1")
        return confirm("The data on this page was changed. Are you sure want to leave this page without saving?");

    else
        return true;
}

function form_is_modified(oForm) {
    var el, opt, hasDefault, i = 0, j;
    while (el = oForm.elements[i++]) {
        switch (el.type) {
            case 'text':
            case 'textarea':
            case 'hidden':
                if (!/^\s*$/.test(el.value) && el.value != el.defaultValue) return true;
                break;
            case 'checkbox':
            case 'radio':
                if (el.checked != el.defaultChecked) return true;
                break;
            case 'select-one':
            case 'select-multiple':
                j = 0, hasDefault = false;
                while (opt = el.options[j++])
                    if (opt.defaultSelected) hasDefault = true;
                j = hasDefault ? 0 : 1;
                while (opt = el.options[j++])
                    if (opt.selected != opt.defaultSelected) return true;
                break;
        }
    }
    return false;
}