详解js如何实现轮播图特效

 

 

  
  

  

  

  

  

  

 
 
 

 
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*{
 margin: 0;
 padding: 0;
}
.clearfix{
 zoom: 1;
}
.clearfix:after{
 content: "";
 display: block;
 height: 0;
 visibility: hidden;
 clear: both;
}
#rollImgBox{
 /*这里让盒子居中，应用到具体页面删除即可*/
 margin: 20px auto;

 /*如果该轮播图不是独占一行，需要将其改为行内块元素*/
 display: block;
 position: relative;
 /*在这里设置装载图片的框框的宽高*/
 width: 947px;
 height: 585px;

 /*在这里设置边框的样式用outline，这样就不会影响到后面的js了
 /*加边框，用outline即可，不会影响实际的距离*/
 outline: 5px solid blue;
 overflow: hidden;
}
#rollImgBox .photos .move img{
 /*在这里设置图片的宽高，与边框的宽高相同*/
 width: 947px;
 height: 585px;
}
#rollImgBox .photos{
 position: relative;
 /*移动的是图片的宽度,左移947px*/
 left: -947px;
}
#rollImgBox:hover{
 cursor: pointer;
}
#rollImgBox .photos div{
 float: left;
}
#rollImgBox .points{
 position: absolute;
 /*在这里修改圆点导航的位置*/
 bottom: 30px;
 right: 170px;/*右下方*/
 text-align: center;
}
#rollImgBox .points span{
 display: inline-block;
 /*在这里可以更改圆点的大小*/
 text-align: center;
 line-height: 66px;
 font-size: 24px;
 font-family: 微软雅黑;
 width: 66px;
 height: 66px;
 background: rgba(112,117,112,.6);
 border-radius: 50%;
 margin-left: 15px;
}
#rollImgBox .points .pointsNow{
 background: rgba(62,255,49,.6);
}

/*左右按钮*/
#rollImgBox .leftPoint{
 width: 60px;
 height: 60px;
 background: rgba(0,0,0,.5);
 text-align: center;
 line-height: 60px;
 position: absolute;
 font-size: 30px;
 color: white;
 top: 290px;
 left: 0;
}
#rollImgBox .rightPoint{
 width: 60px;
 height: 60px;
 background: rgba(0,0,0,.5);
 text-align: center;
 line-height: 60px;
 position: absolute;
 font-size: 30px;
 color: white;
 top: 290px;
 right: 0;
}
#rollImgBox .leftPoint:hover{
 background: rgba(255,0,0,.5);
}
#rollImgBox .rightPoint:hover{
 background: rgba(255,0,0,.5);
}

window.onload = function(){
 let rollImgBox = document.querySelector("#rollImgBox");
 let photos = document.querySelector("#rollImgBox .photos");
 let allimg = document.querySelectorAll("#rollImgBox .move img");
 let index = 2;
 //动态设计移动图片的框框宽高
 //(rollImgBox.offsetWidth)是要剪去边框的宽度
 photos.style.width = (allimg.length)*(rollImgBox.offsetWidth) + "px";
 photos.style.height = rollImgBox.offsetHeight + "px";
 //动态创建小圆点
 let point = new Array();
 let points = document.querySelector("#rollImgBox .points");
 for (let i=0;i<(allimg.length-2);i++){
 point[i] = document.createElement("span");
 point[i].innerHTML = (i+1);
 points.appendChild(point[i]);
 }
 point[0].className = "pointsNow";

 let rollImgIterval = setInterval(function () {
 //图片的轮播
 if (index === allimg.length){
  photos.style.left = 0;
  index = 1;
  photos.style.transition = "0s";
  point[0].className = "pointsNow";
 } else {
  photos.style.transition = "1.5s";
 }
 photos.style.left = -(rollImgBox.offsetWidth)*index + "px";
 index++;
 //小圆点的变换
 for (let j=0;j<(allimg.length-2);j++){
  if (j === index-2){
  point[j].className = "pointsNow";
  } else {
  point[j].className = "";
  }
 }
 //这里是最后一张图片（与展现的第一张一样的图）设置小圆点样式
 if (index === allimg.length){
  point[0].className = "pointsNow";
 }
 },2000);

 //当用户把鼠标放到rollImgBox盒子中，需要查看图片，自动轮播停止
 rollImgBox.onmouseover = function () {
 clearInterval(rollImgIterval);
 };
 rollImgBox.onmouseout = function () {
 rollImgIterval = setInterval(function () {
  //图片的轮播
  if (index === allimg.length){
  photos.style.left = 0;
  index = 1;
  photos.style.transition = "0s";
  point[0].className = "pointsNow";
  } else {
  photos.style.transition = "1.5s";
  }
  photos.style.left = -(rollImgBox.offsetWidth)*index + "px";
  index++;
  //小圆点的变换
  for (let j=0;j<(allimg.length-2);j++){
  if (j === index-2){
   point[j].className = "pointsNow";
  } else {
   point[j].className = "";
  }
  }
  //这里是最后一张图片（与展现的第一张一样的图）设置小圆点样式
  if (index === allimg.length){
  point[0].className = "pointsNow";
  }
 },2000);
 };

 //点击小圆点，跳转到对应的图片位置
 for (let k=0;k<(allimg.length-2);k++){
 point[k].onmousedown = function () {
  photos.style.left = -(rollImgBox.offsetWidth)*(k+1) + "px";
  //小圆点的变换
  for (let j=0;j<(allimg.length-2);j++){
  if (j === k){
   point[j].className = "pointsNow";
  } else {
   point[j].className = "";
  }
  }
  //点击小圆点之后更改index的值
  index = k+2;
 }
 }

 //点击左右方向键，对图片进行滑动
 let leftPoint = document.querySelector('#rollImgBox .leftPoint');
 let rightPoint = document.querySelector('#rollImgBox .rightPoint');
 leftPoint.onclick = function () {
 photos.style.transition = "1s";
 //向左滑动一张图片，并修改index的值（index--）
 let dis = index-2;
 //当dis为1时，圆点到达第一个位置，如果再往左移动一个，圆点应该到达最后一个位置
 if (dis < 1){
  dis = allimg.length-2;
  photos.style.left = 0;
  point[dis-1].className = "pointsNow";
  point[0].className = "";
  index = allimg.length;
 } else {
  photos.style.left = -(rollImgBox.offsetWidth)*dis + "px";
  point[dis-1].className = "pointsNow";
  point[dis].className = "";
 }

 //从第一张顺滑切换到最后一张
 setTimeout(function () {
  if (photos.style.left === '0px'){
  photos.style.left = -(rollImgBox.offsetWidth)*(allimg.length-2) + "px";
  photos.style.transition = '0s';
  index = allimg.length-1;
  }
 },1000);
 index--;
 };
 rightPoint.onclick = function () {
 photos.style.transition = "1s";
 //向右滑动一张图片，并修改index的值（index++）
 let dis = index-1;
 //当dis为5时，圆点到达最后一个位置，如果再往右移动一个，圆点应该到达第一个位置
 if (dis >= (allimg.length-2)){
  photos.style.left = -(rollImgBox.offsetWidth)*(allimg.length-1) + "px";
  point[0].className = "pointsNow";
  point[allimg.length-3].className = "";
  index = 1;
 } else {
  photos.style.left = -(rollImgBox.offsetWidth)*index + "px";
  point[dis].className = "pointsNow";
  point[dis-1].className = "";
 }

 //从最后一张顺滑切换到第一张
 setTimeout(function () {
  if (photos.style.left === ((-(rollImgBox.offsetWidth)*(allimg.length-1))+'px')){
  photos.style.left = -(rollImgBox.offsetWidth) + "px";
  photos.style.transition = '0s';
  index = 2;
  }
 },1000);
 index++;
 };
};