使用JavaScript 实现图片轮播图

第一次写，一直看别人的，默默的看。不多说了 直接上代码。不喜欢说太多，希望能看懂。谢谢。如果有错误，请指出来，我改正，谢谢

css代码：

img {
        width: 100%;
    }

    .liImg {
        width: 900px;
        float: left;
        list-style: none;
    }

    .ulImg {
        width: 90000000px;
        padding: 0;
        margin: 0;
        /*动画时间 2s*/
        transition: all 2s;
    }

    .main {
        width: 900px;
        overflow: hidden;
        position: relative;
        margin: 0 auto;
    }

    .arrows {
        z-index: 999;
        position: absolute;
        padding-top: 350px;
        width: 900px;
    }

    .arrow {
        cursor: pointer;
        background-color: rgba(136, 136, 136, 0.3);
        font-size: 45px;
        color: rgba(136, 136, 136, 0.3);
    }

    /*鼠标经过时更改颜色*/
    .arrow:hover {
        color: rgba(9, 187, 7, 0.5);
        background-color: rgba(9, 187, 7, 0.5);
    }

    .btnDiv {
        width: 960px;
        height: 9px;
        margin: 13px auto;
    }

    .parent {
        margin-left: 23%;
    }

    .divBtn {
        float: left;
        border-radius: 150px;
        background-color: grey;
        width: 30px;
        height: 7px;
        margin-left: 15px;
    }

    .divBtn:hover {
        background-color: red;
    }

html代码：

<div class="main">
    <!--浮动在图片上的左右按钮-->
    <div class="arrows">
        <span title="上一张" class="arrow"> << </span>
        <span title="下一张" class="arrow" style="float: right"> >> </span>
    </div>
    <ul class="ulImg">
        <li class="liImg"><img src="__IMAGES__/slideshow/pic01.jpg"></li>
        <li class="liImg"><img src="__IMAGES__/slideshow/pic02.jpg"></li>
        <li class="liImg"><img src="__IMAGES__/slideshow/pic03.jpg"></li>
        <li class="liImg"><img src="__IMAGES__/slideshow/pic04.jpg"></li>
        <li class="liImg"><img src="__IMAGES__/slideshow/pic05.jpg"></li>
        <li class="liImg"><img src="__IMAGES__/slideshow/pic06.jpg"></li>
        <li class="liImg"><img src="__IMAGES__/slideshow/pic07.jpg"></li>
        <li class="liImg"><img src="__IMAGES__/slideshow/pic08.jpg"></li>
        <li class="liImg"><img src="__IMAGES__/slideshow/pic09.jpg"></li>
        <li class="liImg"><img src="__IMAGES__/slideshow/pic10.jpg"></li>
        <li class="liImg"><img src="__IMAGES__/slideshow/pic11.jpg"></li>
    </ul>
</div>
<!--底部按钮，可以利用css更改样式-->
<div class="btnDiv">
    <div class="parent"></div>
</div>

JavaScript代码：

<script>
    /**
     * 全局变量 count isGo timer
     * */
//    循环的次数
    var count = 0;
    //    循环的方向
    var isGo = false;
    //    循环的时间
    var timer;

    /**
     * 控制图片轮播
     * */
    function showTime() {
        var ulImg = document.getElementsByClassName('ulImg')[0];
        var liImg = document.getElementsByClassName("liImg");
        timer = setInterval(function () {
            if (isGo == false) {
                count++;
                ulImg.style.transform = "translate(" + -900 * count + "px)";
                if (count >= liImg.length - 1) {
                    count = liImg.length - 1;
                    isGo = true;
                }
            } else {
                count--;
                ulImg.style.transform = "translate(" + -900 * count + "px)";
                if (count <= 0) {
                    count = 0;
                    isGo = false;
                }
            }
            divBtnColor();
        }, 5000);
    }

    /**
     * 控制上一页和下一页功能
     * */
    function arrow() {
        var arrow = document.getElementsByClassName('arrow');
        var ulImg = document.getElementsByClassName('ulImg')[0];
        var liImg = document.getElementsByClassName("liImg");
        for (var i = 0; i < arrow.length; ++i) {
            //当鼠标经过的时候，清除定时器timer
            arrow[i].onmouseover = function () {
                clearInterval(timer);
            };
            //当鼠标离开的时候，继续图片轮播
            arrow[i].onmouseout = function () {
                showTime();
            };
            //当点击的时候
            arrow[i].onclick = function () {
                if (this.title == "下一张") {
                    count++;
                    if (count >= liImg.length - 1) {
                        count = 0;
                    }
                } else {
                    count--;
                    if (count <= 0) {
                        count = liImg.length - 1;
                    }
                }
                ulImg.style.transform = "translate(" + -900 * count + "px)";
                divBtnColor();
            }
        }
    }

    //
    <!--根据图片的数量，动态创建底部按钮-->
    function createDivBtn() {
        var divParent = document.getElementsByClassName('parent')[0];
        var chlidBtn = document.createElement('div');
        chlidBtn.className = "divBtn";
        divParent.appendChild(chlidBtn);
    }

    //    控制底部按钮的颜色
    function divBtnColor() {
        var divBtn = document.getElementsByClassName("divBtn");
        for (var i = 0; i < divBtn.length; ++i) {
            divBtn[i].style.backgroundColor = "grey";
        }
        divBtn[count].style.backgroundColor = "red";
    }

    //    控制底部按钮触发的事件
    function divBtnEvent() {
        var divBtn = document.getElementsByClassName("divBtn");
        divBtn[0].style.backgroundColor = "red";

        for (var i = 0; i < divBtn.length; ++i) {

//            这句语句重要，用于标记当前选中的
            divBtn[i].index = i;

            divBtn[i].onmouseover = function () {
                clearInterval(timer);

                for (var j = 0; j < divBtn.length; ++j) {
                    divBtn[j].style.backgroundColor = 'grey';
                }

                divBtn[this.index].style.backgroundColor = 'red';

                if (this.index == divBtn.length - 1) {
                    isGo = true;
                }
                if (this.index == 0) {
                    isGo = false;
                }
                count = this.index;
                var ulImg = document.getElementsByClassName('ulImg')[0];
                ulImg.style.transform = "translate(" + -900 * count + "px)";
            };
            divBtn[i].onmouseout = function () {
                showTime();
            };
        }
    }

    window.onload = function () {
        showTime();
        var liImg = document.getElementsByClassName("liImg");
        for (var j = 0; j < liImg.length; ++j) {
            createDivBtn();
        }
        arrow();
        divBtnEvent();

    }
</script>

效果图： 图片轮播图

好了，请耐心看，必要的注释，已经做了，看完应该有一定的理解