我正在嘗試獲取部分在視口中的位置并向它們添加活動類，但代碼不起作用。任何人都可以幫忙嗎？// Get the position of the sections in viewportfunction isInViewport(element) {    const rect = element.getBoundingClientRect();    return (      rect.top >= 0 &&      rect.left >= 0 &&      rect.bottom <= (window.innerHeight || document.documentElement.clientHeight) &&      rect.right <= (window.innerWidth || document.documentElement.clientWidth)    );  }//add active class to sections in viewport function setActiveClass(){    for (let i=0; i <= sectionsArr.length; i++){        if (isInViewport(sections[i])){            sections[i].classList.add("your-active-class");        }else{            sections[i].classList.remove("your-active-class");        }    }}