前端设计轮播图

前端设计轮播图可以使用一些现成的插件库，比如swiper、slick等，也可以自己手写实现。以下是一个简单的手写实现轮播图的示例代码：

HTML部分：

<div class="carousel">
  <ul class="carousel-list">
    <li class="carousel-item active"><img src="image1.jpg"></li>
    <li class="carousel-item"><img src="image2.jpg"></li>
    <li class="carousel-item"><img src="image3.jpg"></li>
  </ul>
  <div class="carousel-dots">
    <span class="dot active"></span>
    <span class="dot"></span>
    <span class="dot"></span>
  </div>
  <button class="carousel-prev">Prev</button>
  <button class="carousel-next">Next</button>
</div>

CSS部分：

.carousel {
  position: relative;
}
.carousel-list {
  list-style: none;
  margin: 0;
  padding: 0;
  position: relative;
}
.carousel-item {
  position: absolute;
  top: 0;
  left: 0;
  opacity: 0;
  transition: opacity 0.5s ease-in-out;
}
.carousel-item.active {
  opacity: 1;
}
.carousel-dots {
  position: absolute;
  bottom: 20px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
}
.dot {
  width: 15px;
  height: 15px;
  border-radius: 50%;
  background-color: #ccc;
  margin: 0 10px;
  cursor: pointer;
}
.dot.active {
  background-color: #333;
}
.carousel-prev,
.carousel-next {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  background-color: #333;
  color: #fff;
  border: none;
  padding: 10px;
  cursor: pointer;
}
.carousel-prev {
  left: 20px;
}
.carousel-next {
  right: 20px;
}

JavaScript部分：

const carouselList = document.querySelector('.carousel-list');
const carouselItems = document.querySelectorAll('.carousel-item');
const dots = document.querySelectorAll('.dot');
const prevBtn = document.querySelector('.carousel-prev');
const nextBtn = document.querySelector('.carousel-next');
let currentIndex = 0;

function setActive(index) {
  carouselItems[currentIndex].classList.remove('active');
  dots[currentIndex].classList.remove('active');
  carouselItems[index].classList.add('active');
  dots[index].classList.add('active');
  currentIndex = index;
}

function prev() {
  let index = currentIndex - 1;
  if (index < 0) {
    index = carouselItems.length - 1;
  }
  setActive(index);
}

function next() {
  let index = currentIndex + 1;
  if (index >= carouselItems.length) {
    index = 0;
  }
  setActive(index);
}

dots.forEach((dot, index) => {
  dot.addEventListener('click', () => {
    setActive(index);
  });
});

prevBtn.addEventListener('click', prev);
nextBtn.addEventListener('click', next);

setActive(currentIndex);
setInterval(next, 3000);

注意：以上代码只是一个简单的示例，实际开发中还需要考虑更多的细节和兼容性问题。