在此插入代码
//全选全不选
selectAll.click(function() {
    if (this.checked) {
        selectAllLabel.hide();
        deselectAllLabel.show();
        langs.prop("checked", true);
    } else {
        selectAllLabel.show();
        deselectAllLabel.hide();
        langs.prop("checked", false);
    }
});
//反选
invertSelect.click(function() {
    var arr = [].slice.call(langs);
    arr.map(function(x) {
        $(x).prop("checked", !($(x).is(":checked")));
    });
    langs.change();//反选时全选全部选的状态
});
//判断是否全选
langs.change(function(event) {

    var arr = [].slice.call(langs);
    function isChecked(x){
         return $(x).is(":checked");
    }
    if (arr.every(isChecked)){
        selectAllLabel.hide();
        deselectAllLabel.show();
        selectAll.prop("checked", true);
    }else {
        selectAllLabel.show();
        deselectAllLabel.hide();
selectAll.prop("checked", false);
    }

});