//函数isAll()判断是否已经全选，改变selectAll状态
function isAll() {
    if (langs.filter(':checked').length === langs.length) {
        selectAll.prop('checked', true);
        selectAllLabel.hide();
        deselectAllLabel.show();
    } else {
        selectAll.prop('checked', false);
        selectAllLabel.show();
        deselectAllLabel.hide(); 
    }
}
//绑定全选/全不选框
selectAll.click(function () {
    if (selectAll.prop('checked')) {
        langs.prop("checked", true);
    } else {
        langs.prop("checked", false);
    }
    isAll();
})
//绑定反选框
invertSelect.click(function () {
    langs.map(function () {
        $(this).prop("checked", !$(this).prop("checked"));
    })
    isAll();
})
//绑定语言框
langs.click(function () {
    isAll();
})