我使用javascript更新的数据幻灯片无法正常工作

Question

我正在使用javaScript更新我的数据幻灯片值，它也在更新但不影响滑块。

 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 Pasted this in Chrome inspect element

 All the names are right

var firstName = document.getElementById('firstName');
var lastName = document.getElementById('lastName');
var dataSlide = document.getElementById('dataSlide');
   
function information_count(){
    if (firstName.value == '' || lastName.value == '') {
        dataSlide.setAttribute('data-slide', 'none');
    } else {
        dataSlide.setAttribute('data-slide', 'next');
    }
}