使用原生的javascript来实现轮播图

下面看下js轮播图的实现代码，具体代码如下所示：

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title></title>
  <style type="text/css">
    * {
      padding: 0;
      margin: 0;
      list-style: none;
      border: 0;
    }
    .all {
      width: 500px;
      height: 200px;
      padding: 7px;
      border: 1px solid #ccc;
      margin: 100px auto;
      position: relative;
    }
    .screen {
      width: 500px;
      height: 200px;
      overflow: hidden;
      position: relative;
    }
    .screen li {
      width: 500px;
      height: 200px;
      overflow: hidden;
      float: left;
    }
    .screen ul {
      position: absolute;
      left: 0;
      top: 0px;
      width: 3000px;
    }
    .all ol {
      position: absolute;
      right: 10px;
      bottom: 10px;
      line-height: 20px;
      text-align: center;
    }
    .all ol li {
      float: left;
      width: 20px;
      height: 20px;
      background: #fff;
      border: 1px solid #ccc;
      margin-left: 10px;
      cursor: pointer;
    }
    .all ol li.current {
      background: yellow;
    }
    #arr {
      display: none;
    }
    #arr span {
      width: 40px;
      height: 40px;
      position: absolute;
      left: 5px;
      top: 50%;
      margin-top: -20px;
      background: #000;
      cursor: pointer;
      line-height: 40px;
      text-align: center;
      font-weight: bold;
      font-family: '黑体';
      font-size: 30px;
      color: #fff;
      opacity: 0.3;
      border: 1px solid #fff;
    }
    #arr #right {
      right: 5px;
      left: auto;
    }
  </style>
</head>
<body>
<div class="all" id='box'>
  <div class="screen">
    <ul>
      <li><img src="images/1.jpg" width="500" height="200"/></li>
      <li><img src="images/2.jpg" width="500" height="200"/></li>
      <li><img src="images/3.jpg" width="500" height="200"/></li>
      <li><img src="images/4.jpg" width="500" height="200"/></li>
      <li><img src="images/5.jpg" width="500" height="200"/></li>
    </ul>
    <ol>
    </ol>
  </div>
  <div id="arr"><span id="left"><</span><span id="right">></span></div>
</div>
<script>
  function $(element) {
    return document.getElementById(element);
  }
  var box = $("box");
  var screen = box.children[0];
  var ul = screen.children[0];
  var ulLis = ul.children;
  var ol = screen.children[1];
  var arr = $("arr");
  var left = $("left");
  var right = $("right");
  //动态创建小图标
  for (var i = 0; i < ulLis.length; i++) {
    var li = document.createElement("li");
    li.innerHTML = i + 1;
    ol.appendChild(li);
  }
  //设置这些个小图标
  var olLis = ol.children;
  var imgWidth = screen.offsetWidth;
  for (var j = 0; j < olLis.length; j++) {
    olLis[j].index = j;
    olLis[j].onmouseover = function () {
      //排他思想
      for (var i = 0; i < olLis.length; i++) {
        olLis[i].className = "";
      }
      this.className = "current";
      var target = -imgWidth * this.index;
      cutton(ul, target, 20);
      //为了让点击事件和小面的小图标能够一一对应，设置他们的索引值相同
      pic = square = this.index;
    }
  }
  //给小图标设置一个初始样式
  ol.children[0].className = "current";
  //给ul追加一张图
  ul.appendChild(ul.children[0].cloneNode(true));
  //设置箭头的显示与隐藏
  box.onmouseover = function () {
    arr.style.display = "block";
    //鼠标放上去的时候，不再自动滚动
    clearInterval(timer);
  }
  box.onmouseout = function () {
    arr.style.display = "none";
    //鼠标离开的时候，继续自动滚动
    timer = setInterval(playNext, 1000);
  }
  //设置点击左右小箭头的事件且要求小图标要跟着变化
  //1.设置点击右侧箭头
  var pic = 0;//记录当前为第几项用
  var square = 0;//记录小图标的索引值
  /* right.onclick = function () {//存在的问题是当移动到最后一张的时候，无法跳转到第一张
   pic++;
   var target = -pic * imgWidth;
   cutton(ul, target, 20);
   }*/
  //方法改进
  /*right.onclick = function () {
   //先对pic做一个判断，当pic的值为5的时候，实现一个跳转
   if (pic == ulLis.length - 1) {
   ul.style.left = 0;
   pic = 0;
   }
   pic++;
   var target = -pic * imgWidth;
   cutton(ul, target, 20);
   if (square == olLis.length - 1) {
   square = -1;//下面会加一，就变成了0
   }
   square++;
   //排他思想
   for (var i = 0; i < olLis.length; i++) {
   olLis[i].className = "";
   }
   olLis[square].className = "current";
   }*/
  //使用封装函数
  right.onclick = function () {
    playNext();
  }
  //2.设置点击左侧箭头
  left.onclick = function () {//要判断一下当pic为零时的情况
    if (pic == 0) {
      ul.style.left = -imgWidth * (ulLis.length - 1) + "px";//要记得加单位
      pic = ulLis.length - 1;//给pic重新赋一个值
    }
    pic--;
    var target = -pic * imgWidth;
    cutton(ul, target, 20);
    //设置小图标样式
    if (square == 0) {
      square = olLis.length;
    }
    square--;
    for (var i = 0; i < olLis.length; i++) {
      olLis[i].className = "";
    }
    olLis[square].className = "current";
  }
  //设置自动滚动
  //1.封装点击右侧小箭头事件
  function playNext() {
    //先对pic做一个判断，当pic的值为5的时候，实现一个跳转
    if (pic == ulLis.length - 1) {
      ul.style.left = 0;
      pic = 0;
    }
    pic++;
    var target = -pic * imgWidth;
    cutton(ul, target, 20);
    if (square == olLis.length - 1) {
      square = -1;//下面会加一，就变成了0
    }
    square++;
    //排他思想
    for (var i = 0; i < olLis.length; i++) {
      olLis[i].className = "";
    }
    olLis[square].className = "current";
  }
  //2.调用这个封装的函数，并且设置一个间歇性计时器
  var timer = null;
  timer = setInterval(playNext, 1000);
  //封装函数
  function cutton(obj, target, stp) {
    clearInterval(obj.timer);
    obj.timer = setInterval(function () {
      var step = stp;
      step = obj.offsetLeft > target ? -step : step;
      if (Math.abs(obj.offsetLeft - target) >= Math.abs(step)) {
        obj.style.left = obj.offsetLeft + step + "px";
      } else {
        obj.style.left = target + "px";
        clearInterval(obj.timer);
      }
    }, 15)
  }
</script>
</body>
</html>

补充：原生javascript实现banner图自动轮播切换

一般在做banner轮播图的时候都是用jquery，因为代码少，方便，不需要花费很长的时间去获取某个元素作为变量，然后再进行操作，只要一个$就搞定了。但是今天我用原生的javascript做了一下这个轮播效果，感觉还行，以下是部分js源代码，仅供参考！文章底部查看效果演示。

1、鼠标离开banner图，每隔2s切换一次；

2、鼠标滑过下方的小按钮，可以切换图片；

3、鼠标点击左右按钮，可以切换图片。

var oPic,oLi,anniu,aLi,aLength,num,timer,oG,_index,oSpan;
window.onload = function(){
  oPic = document.getElementsByClassName("pic")[0];
  oLi = oPic.getElementsByTagName("li");
  anniu = document.getElementsByClassName("anniu")[0];
  aLi = anniu.getElementsByTagName("li");
  aLength = aLi.length;
  num = 0;
  oG = document.getElementsByClassName("g")[0];
  oSpan = oG.getElementsByTagName("span");
  oLeft = oSpan[0];
  oRight = oSpan[1];
  start();
  oG.onmouseover = end;
  oG.onmouseout = start;
  for(var j=0; j<aLength; j++){
    aLi[j].index = j;
    aLi[j].onmouseover = change;
  }
  oRight.onclick = time;
  oLeft.onclick = times;
}
//自动轮播开始或结束
function start(){
    timer = setInterval(time,2000);
    hide();
}
function end(){
  clearInterval(timer);
  show();
}
//图片切换++
function time(){
  for(var i=0; i<aLength; i++){
    oLi[i].style.display = "none";
    aLi[i].className = "";
  }
  num++;
  num = num % 4;
  oLi[num].style.display = "block";
  aLi[num].className = "on";
}
//图片切换--
function times(){
  for(var i=0; i<aLength; i++){
    oLi[i].style.display = "none";
    aLi[i].className = "";
  }
  num--;
  num = (num+4)%4;
  oLi[num].style.display = "block";
  aLi[num].className = "on";
}
//鼠标滑过按钮，图片轮播
function change(){
  _index = this.index;
  for(var k=0; k<aLength; k++){
    aLi[k].className = "";
    oLi[k].style.display = "none";
  }
  aLi[_index].className = "on";
  oLi[_index].style.display = "block";
}
//左右按钮显示或隐藏
function show(){
  oSpan[0].style.display = "block";
  oSpan[1].style.display = "block";
}
function hide(){
  oSpan[0].style.display = "none";
  oSpan[1].style.display = "none";
}

以上所述是小编给大家介绍的使用原生的javascript来实现轮播图，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对我们网站的支持！