如何在div中的特定锚元素上添加/删除类? [英] How to add/remove class to specific anchor elements inside div?
问题描述
我有一个如下所示的DOM,仅在第三个锚元素(仅 4th 和 5th 元素)之后可以添加/删除类
I have a DOM as shown below in which to add/remove class only after third anchor element (only 4th and 5th element).
<div class="featured-block">
<a href="" class="featured-block__item cf"> <!-- 1st element -->
</a>
<a href="" class="featured-block__item cf"> <!-- 2nd element -->
</a>
<a href="" class="featured-block__item cf"> <!-- 3rd element -->
</a>
<a href="" class="featured-block__item cf"> <!-- Add/remove (4th element)-->
</a>
<a href="" class="featured-block__item cf"> <!-- Add/remove (5th element)-->
</a>
</div>
我已使用以下 JS代码,以便在第4 个以上DOM中添加/删除类features-block__item-active 和第五名.
I have used the following JS code in order to add/remove class featured-block__item-active in the DOM above at the 4th and 5th position.
我现在遇到的问题是它在第4位和第5位位置上添加/删除班级,然后在上再次添加/删除班级>第一/第二/第三位置(我不想要).
The problem which I am having right now is that it adds/removes the class at 4th and 5th position and then adds/removes class again at 1st/2nd/3rd position (which I don't want).
document.querySelectorAll('.featured-block .featured-block__item')[3].classList.add('featured-block__item-active'); // Line Z (Adding at 4th element)
const pics = document.querySelectorAll('.featured-block .featured-block__item');
function toggleClass() {
const activePic = document.querySelector('.featured-block__item.featured-block__item-active');
const activeIndex = Array.prototype.indexOf.call(pics, activePic);
const nextIndex = activeIndex === lastPic ? 0 : activeIndex + 1;
const nextPic = pics[nextIndex];
setTimeout(() => activePic.classList.remove('featured-block__item-active'), transitionDelay); // Line A
setTimeout(() => nextPic.classList.add('featured-block__item-active'), totalDelay); // Line B
}
setInterval(toggleClass, intervalDelay);
问题陈述:
我想知道我应该对上述 JS 进行哪些更改,以使其仅在第4 个添加/删除feature-block__item-active类>和第5 位.
I am wondering what changes I should make in the JS above so that it add/remove featured-block__item-active class only at 4th and 5th position.
我认为,我需要在 Z线, A线和 B线进行更改.
I think, I need to make changes at Line Z, Line A and Line B.
推荐答案
只需将0更改为3.
document.querySelectorAll('.featured-block .featured-block__item')[3].classList.add('featured-block__item-active'); // Line Z (Adding at 4th element)
const pics = document.querySelectorAll('.featured-block .featured-block__item');
const lastPic = pics.length - 1;
const transitionDuration = 500; // matches CSS
let transitionDelay = 3 * 1000;
const totalDelay = transitionDuration + transitionDelay;
const intervalDelay = (transitionDuration * 2) + transitionDelay;
function toggleClass() {
const activePic = document.querySelector('.featured-block__item.featured-block__item-active');
const activeIndex = Array.prototype.indexOf.call(pics, activePic);
const nextIndex = activeIndex === lastPic ? 3 : activeIndex + 1;
const nextPic = pics[nextIndex];
setTimeout(() => activePic.classList.remove('featured-block__item-active'), transitionDelay);
setTimeout(() => nextPic.classList.add('featured-block__item-active'), totalDelay);
}
setInterval(toggleClass, intervalDelay);
.featured-block__item { border: solid lime 1px;}
.featured-block__item-active{background-color: #DDDDFF;}
<div class="featured-block">
<a href="" class="featured-block__item cf">1 </a>
<a href="" class="featured-block__item cf">2 </a>
<a href="" class="featured-block__item cf">3 </a>
<a href="" class="featured-block__item cf">4 </a>
<a href="" class="featured-block__item cf">5 </a>
</div>
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