老师帮忙检查是否正确

const  slider = document.querySelector('.slider');
      const leftbtn = document.getElementById('leftbtn'),
            rightbtn = document.getElementById('rightbtn');
      
      class ButtonSlider extends BaseSlider {
        constructor(el,options) {
          super(el,options);
          this._bindEvent();
        }
        _bindEvent() {
          leftbtn.addEventListener('click',()=>{
            this.prev();
          });
          rightbtn.addEventListener('click',()=>{
            this.next();
          });
          slider.addEventListener('mouseenter',()=>{
            leftbtn.style.display = 'block';
            rightbtn.style.display = 'block';
          })
          slider.addEventListener('mouseleave',()=>{
            leftbtn.style.display = 'none';
            rightbtn.style.display = 'none';
          })
        }
      }
      new ButtonSlider(slider,{speed:2000,initialIndex:1});