js原生轮播图插件制作

<div id="banner"></div>

<script>
        bannerArea(document.getElementById("banner"),[
            {imgUrl:"图片",
            link:"跳转链接"
        },
            {imgUrl:"图片",
            link:"跳转链接"
        },
            {imgUrl:"图片",
            link:"跳转链接"
        }
        ])
</script> 

// 两个参数，第一个轮播图区域，第二个是配置
function bannerArea(areaDom, options) {
    var imgArea = document.createElement("div");
    var numberArea = document.createElement("div");
    var curIndex = 0;//第几张轮播图
    var changeTimer = null;
    var changeDuration = 1000;//间隔
    var timer = null;
    
    initImg();//创建一个区域来显示图片
    
    initNumber();//创建区域显示角标
    
    setStatus();//设置状态
    
    autoChange();//自动切换
 
    //下面是局部函数
 
    //创建图片，并且设置样式
    function initImg() {
        imgArea.style.width = "100%";
        imgArea.style.height = "100%";
        imgArea.style.display = "flex";
        imgArea.style.overflow = "hidden";
        for (let i = 0; i < options.length; i++) {
            var obj = options[i];
            var img = document.createElement("img");
            img.src = obj.imgUrl;
            img.style.width = "100%";
            img.style.height = "100%";
            img.style.margin = "0";
            img.addEventListener("click", function () {
                location.href = options[i].link;
            })
            imgArea.appendChild(img);
        }
        imgArea.addEventListener("mouseenter", function () {
            clearInterval(changeTimer);
            changeTimer = null;
        })
        imgArea.addEventListener("mouseleave", function () {
            autoChange();
        })
        areaDom.appendChild(imgArea);
    }
    //创建角标元素和设置样式
    function initNumber() {
        numberArea.style.textAlign = "center";
        numberArea.style.marginTop = "-25px";
        for (let i = 0; i < options.length; i++) {
            var sp = document.createElement("span");
            sp.style.width = "12px";
            sp.style.height = "12px";
            sp.style.background = "lightgray";
            sp.style.display = "inline-block";
            sp.style.margin = "0 7px";
            sp.style.borderRadius = "50%";
            sp.style.cursor = "pointer";
            sp.addEventListener("click", function () {
                curIndex = i;
                setStatus();
            })
            numberArea.appendChild(sp);
        }
        areaDom.appendChild(numberArea);
    }
 
    //设置角标区域状态
    function setStatus() {
        //设置圆圈的背景颜色
        for (var i = 0; i < options.length; i++) {
            if (i === curIndex) {
                //设置背景颜色为选择
                numberArea.children[i].style.background = "rgb(222 57 57)";
            } else {
                //非选择
                numberArea.children[i].style.background = "lightgray";;
            }
 
        }
        //显示图片
        var start = parseInt(imgArea.children[0].style.marginLeft);
        var end = curIndex * -100;
        var dis = end - start;
        var duration = 500;
        var speed = dis / duration;
        if (timer) {
            clearInterval(timer);
        }
        timer = setInterval(function () {
            start += speed * 20;
            imgArea.children[0].style.marginLeft = start + "%";
            if (Math.abs(end - start) < 1) {
                imgArea.children[0].style.marginLeft = end + "%";
                clearInterval(timer);
            }
        }, 20)
    }
    //自动切换
    function autoChange() {
        if (changeTimer) {
            return;
        }
        changeTimer = setInterval(function () {
            if (curIndex === options.length - 1) {
                curIndex = 0;
            } else {
                curIndex++;
            }
            setStatus();
        }, changeDuration)
    }
 
}