简易轮播器、无缝轮播器

功能：点击切换，自动切换
html

<div class="">
            <div class="container-image">
                <img class="banner-img" src="https://ss1.bdstatic.com/70cFuXSh_Q1YnxGkpoWK1HF6hhy/it/u=3721486562,2041162213&fm=27&gp=0.jpg" >
                <img class="banner-img" src="https://ss0.bdstatic.com/70cFuHSh_Q1YnxGkpoWK1HF6hhy/it/u=3377153203,4138457011&fm=26&gp=0.jpg" >
                <img class="banner-img" src="https://ss0.bdstatic.com/70cFuHSh_Q1YnxGkpoWK1HF6hhy/it/u=2018040178,138482694&fm=26&gp=0.jpg" >
            </div>

            <div class="tab">
                <span></span>
                <span></span>
                <span></span>
            </div>
        </div>

css

.container-image{
            position: relative;
            display: flex;
            height: 500px;
            justify-content: center;
            align-items:center;
        }
        .container-image img{
            position: absolute;
            display: block;
            margin:auto;
            opacity: 0;
            transition: opacity 2s;
        }
        .tab{
            text-align: center;
        }
        .tab span{
            display: inline-block;
            width:10px;
            height:10px;
            background: #000;
            -webkit-border-radius:5px;
            -moz-border-radius:5px;
            border-radius:5px;
        }

js

/*
        *   轮播图  轮播图的淡入淡出效果可以通过给样式添加transition：opacity:2s;2s代表时间
        * */
        $(".tab span").css("background","red");
        //获取各个节点
        let imageList = document.getElementsByClassName("banner-img");
        imageList[0].style.opacity = 1;
        let tabList = document.getElementsByClassName("tab")[0].getElementsByTagName("span");
        let number = 0;
        for(let i = 0;i < tabList.length; i++){
            tabList[i].index = i;
            tabList[i].onclick = function () {
                //遍历所有的img元素，opacity设置为0，点击的俄元素设置为1
                console.log("this是" + this.index)
                console.log("i是" + i)
                console.log("timeId" + timeId)
                clearInterval(timeId);
                for(let j = 0;j < tabList.length;j++){
                    imageList[tabList[j].index].style.opacity = 0;
                }
                number = tabList[i].index;
                imageList[tabList[i].index].style.opacity = 1;
                timeId = setInterval(Time,3000);
            }
        }
        function Time() {
            number++;
            console.log(number)
            if(number < 3){
                for(let j = 0;j < tabList.length;j++){
                    imageList[tabList[j].index].style.opacity = 0;
                }
                imageList[number].style.opacity = 1;
                console.log("第一个" + number)
            }else{
                number = 0;
                for(let j = 0;j < tabList.length;j++){
                    imageList[tabList[j].index].style.opacity = 0;
                }
                imageList[number].style.opacity = 1;
                console.log("第二个"  + number)
            }
        }
        clearInterval(timeId);  //在调用定时器要先清除定时器，不然会让定时器一直叠加，使得轮播速度越来越快
        var timeId = setInterval(Time,3000);

无缝轮播器

html:\
<div class="container">   <!--  无缝轮播-->
          <div class="carousel-image" style="left: -500px;">
                <img src="https://ss1.bdstatic.com/70cFuXSh_Q1YnxGkpoWK1HF6hhy/it/u=339056085,2254279736&fm=27&gp=0.jpg" class="image">
                <img src="https://ss0.bdstatic.com/70cFvHSh_Q1YnxGkpoWK1HF6hhy/it/u=1465757463,2243826297&fm=27&gp=0.jpg" class="image">
                <img src="https://ss3.bdstatic.com/70cFv8Sh_Q1YnxGkpoWK1HF6hhy/it/u=836142732,2789906085&fm=27&gp=0.jpg" class="image">
                <img src="https://ss1.bdstatic.com/70cFuXSh_Q1YnxGkpoWK1HF6hhy/it/u=339056085,2254279736&fm=27&gp=0.jpg" class="image">
                <img src="https://ss0.bdstatic.com/70cFvHSh_Q1YnxGkpoWK1HF6hhy/it/u=1465757463,2243826297&fm=27&gp=0.jpg" class="image">

            </div>
            <div style="position: absolute;top: 150px;width: 500px;display: flex;justify-content: space-between;color:white;">
                <span id="pre">pre</span>
                <span id="next">next</span>
            </div>
        </div>

css:
.container{
            position: relative;
            width:500px;
            height: 330px;
            overflow: hidden;
        }
        .carousel-image{
            position: absolute;
            width:3000px;
        }


js:
let pre = document.getElementById("pre");
        let next = document.getElementById("next");
        let carouselImage = document.getElementsByClassName("carousel-image");
        console.log(carouselImage[0].style.left)   //注意了：.style.left只能获取有内联样式的标签的left，否则为空。.offsetLeft才可以获取标签的left
        //向右滑动
        next.onclick = function () {
            animate(-500);
        }
        pre.onclick = function () {
            animate(500);
        }
        //移动函数
        function animate(offset){    //为什么第二次go()函数调用时，offset为NaN
            var leftDistance = parseInt(carouselImage[0].style.left) + offset;
            var newoffset = offset;
            var speed = newoffset/20;   //注意：如果这行代码放在go()函数里面，go()第二次执行的时候newoffset为NaN,导致定时器失效。应该是涉及到了作用域链的知识点。  每一步移动的距离  speed>0是向右
            //动画函数
            function go(newoffset){
                currentLeft = carouselImage[0].style.left;   //当前图片的位置
                if(speed > 0 && leftDistance > parseInt(currentLeft) || speed < 0 && leftDistance < parseInt(currentLeft)){
                    carouselImage[0].style.left =  parseInt(currentLeft) + speed + "px";
                    setTimeout(go,10);
                }else if(leftDistance < -1500){
                    carouselImage[0].style.left = -500 + "px";
                }else if(leftDistance > -500){
                    carouselImage[0].style.left = -1500 + "px";

                }
            }
            go(newoffset);
        }

效果图

5a2beef312a9976ec67f3498b4cf391.png

https://blog.csdn.net/konghouy/article/details/81407492