jQuery的方法实现轮播图，实现的轮播图最少由3幅图组成，每隔一段时间自动切换到下一幅图；鼠标停留时显示左右切换的按钮，点击左右按钮可以切换到上一幅或下一幅图；点击图下面的圆形下标，切换到对应的图。图片切换需无缝切换，首尾图片切换时无违和感的代码

好的，以下是基于jQuery实现轮播图的代码：

HTML结构：

<div class="carousel">
  <ul class="carousel-list">
    <li><img src="img1.jpg" alt=""></li>
    <li><img src="img2.jpg" alt=""></li>
    <li><img src="img3.jpg" alt=""></li>
  </ul>
  <ul class="carousel-nav">
    <li class="active"></li>
    <li></li>
    <li></li>
  </ul>
  <a href="#" class="carousel-prev"></a>
  <a href="#" class="carousel-next"></a>
</div>

CSS样式：

.carousel {
  position: relative;
  width: 600px;
  height: 400px;
  overflow: hidden;
}
.carousel-list {
  position: absolute;
  left: 0;
  top: 0;
  width: 1800px;
  height: 400px;
  margin: 0;
  padding: 0;
  list-style: none;
}
.carousel-list li {
  float: left;
}
.carousel-nav {
  position: absolute;
  left: 50%;
  bottom: 20px;
  transform: translateX(-50%);
  margin: 0;
  padding: 0;
  list-style: none;
}
.carousel-nav li {
  display: inline-block;
  width: 10px;
  height: 10px;
  margin: 0 5px;
  border-radius: 50%;
  background-color: #ccc;
  cursor: pointer;
}
.carousel-nav li.active {
  background-color: #f00;
}
.carousel-prev, .carousel-next {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  width: 20px;
  height: 20px;
  background-color: #ccc;
  opacity: 0.5;
  cursor: pointer;
}
.carousel-prev {
  left: 20px;
}
.carousel-next {
  right: 20px;
}

jQuery代码：

$(function () {
  var $carousel = $('.carousel'),
      $list = $carousel.find('.carousel-list'),
      $items = $list.find('li'),
      $nav = $carousel.find('.carousel-nav'),
      $navItems = $nav.find('li'),
      $prev = $carousel.find('.carousel-prev'),
      $next = $carousel.find('.carousel-next'),
      itemWidth = $items.outerWidth(true),
      itemCount = $items.length,
      currentIndex = 0,
      isAnimating = false,
      timer = null,
      interval = 3000;

  // 初始化
  $list.css('width', itemWidth * itemCount);
  $navItems.eq(currentIndex).addClass('active');

  // 自动轮播
  function play() {
    timer = setInterval(function () {
      next();
    }, interval);
  }

  // 停止轮播
  function stop() {
    clearInterval(timer);
  }

  // 切换到下一张图片
  function next() {
    if (isAnimating) {
      return;
    }
    isAnimating = true;
    currentIndex++;
    if (currentIndex >= itemCount) {
      currentIndex = 0;
    }
    $navItems.removeClass('active').eq(currentIndex).addClass('active');
    $list.animate({
      left: -itemWidth * currentIndex
    }, function () {
      isAnimating = false;
    });
  }

  // 切换到上一张图片
  function prev() {
    if (isAnimating) {
      return;
    }
    isAnimating = true;
    currentIndex--;
    if (currentIndex < 0) {
      currentIndex = itemCount - 1;
    }
    $navItems.removeClass('active').eq(currentIndex).addClass('active');
    $list.animate({
      left: -itemWidth * currentIndex
    }, function () {
      isAnimating = false;
    });
  }

  // 点击圆形下标切换图片
  $navItems.on('click', function () {
    var index = $(this).index();
    if (index === currentIndex) {
      return;
    }
    currentIndex = index;
    $navItems.removeClass('active').eq(currentIndex).addClass('active');
    $list.animate({
      left: -itemWidth * currentIndex
    });
  });

  // 鼠标移入停止轮播，显示左右按钮
  $carousel.on('mouseenter', function () {
    stop();
    $prev.stop().animate({
      left: 0,
      opacity: 1
    });
    $next.stop().animate({
      right: 0,
      opacity: 1
    });
  });

  // 鼠标移出开始轮播，隐藏左右按钮
  $carousel.on('mouseleave', function () {
    play();
    $prev.stop().animate({
      left: -20,
      opacity: 0.5
    });
    $next.stop().animate({
      right: -20,
      opacity: 0.5
    });
  });

  // 点击左右按钮切换图片
  $prev.on('click', function () {
    prev();
  });
  $next.on('click', function () {
    next();
  });

  // 开始轮播
  play();
});

这份代码实现了基本的轮播图功能，包括自动轮播、鼠标移入移出、左右切换按钮、圆形下标切换等，图片切换无缝，首尾图片切换时也没有违和感。