JavaScript(二）

好像没有什么知识点,那么直接上案例

在这里插入图片描述

实现上下图片的切换,，一共有10张图片

<body>
    <img id="icon" src="img/icon_01.png" alt="">
    <p></p>
    <button id="prev">上一张</button>
    <button id="next">下一张</button>
<script>
    window.onload = function () {
        // 1. 获取需要的标签
        var icon = document.getElementById("icon");
        var prev = document.getElementById("prev");
        var next = document.getElementById("next");
        // 2. 监听按钮的点击
        var maxIndex = 9, minIndex = 1, currentIndex = minIndex;# 默认是第一张
        prev.onclick = function () {
            if (currentIndex === minIndex){ // 边界值
                currentIndex = maxIndex;
            }else { // 正常情况
                currentIndex --;
            }

            icon.setAttribute("src", "img/icon_0" + currentIndex + ".png");

            console.log(icon.src);
        };
        next.onclick = function () {
             if (currentIndex === maxIndex){ // 边界值
                 currentIndex = minIndex;
             }else { // 正常情况
                 currentIndex ++;
             }
             icon.setAttribute("src", "img/icon_0" + currentIndex + ".png");
            console.log(icon.src);
        };
    }
</script>
</body>

显示隐藏图片

在这里插入图片描述

<body>
    <button id="btn">隐藏</button>
    <p></p>
    <img src="img/img_01.jpg" alt="">
<script>
    window.onload = function () {
        // 1. 获取事件源和相关的元素
        var btn = document.getElementById("btn");
        var img = document.getElementsByTagName("img")[0];
        // 2.绑定事件
        btn.onclick = function () {
            // 3. 事件的驱动程序
            if(btn.innerText === "隐藏"){
                img.style.display = "none";
                btn.innerText = "显示";
            }else {
                img.style.display = "block";
                btn.innerText = "隐藏";
            }
        }
    }
</script>
</body>

来个简单的的例子

<body>
    <img id="logo" src="img/img1.jpg" alt="" width="258">
<script>
    window.onload = function () {
        // 1. 获取需要的标签
        var logo = document.querySelector("#logo");
        // console.log(logo);

        // 2. 绑定事件
        logo.onmouseover = function () {
            console.log("鼠标进入图片");
            // logo.src = "img/img2.jpg";
            this.src = "img/img2.jpg";
            //console.log(this);
        };
        logo.onmouseout = function () {
            console.log("鼠标离开图片");
            this.src = "img/img1.jpg";
        };
        logo.onmousemove = function () {
            console.log("鼠标在图片上移动");
        }
    }
</script>
</body>

难度上升
在这里插入图片描述
点击下面的图片上面两个都换成对应的额

<html lang="en">
<head>
    <meta charset="UTF-8">
    <title></title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        body{
            margin: 50px;
        }
        #fj{
            list-style: none;
        }
        #fj li{
            float: left;
            margin-left: 10px;
        }
        #big_img{
            margin-left: 10px;
        }
        #des{
            margin: 10px;
            color: orangered;
            font-size: 20px;
        }
    </style>
</head>
<body>
    <!--大图描述-->
    <p id="des">蒲公英</p>
    <!--大图展示-->
    <img id="big_img" src="img/1.jpg" alt="" width="540">
    <!--小图列表-->
    <ul id="fj">
        <li>
            <a href="img/1.jpg" title="蒲公英">
                <img src="img/1.jpg" width="100" alt="蒲公英">
            </a>
        </li>
        <li>
            <a href="img/2.jpg" title="热气球">
                <img src="img/2.jpg" width="100" alt="热气球">
            </a>
        </li>
        <li>
            <a href="img/3.jpg" title="别致小屋">
                <img src="img/3.jpg" width="100" alt="别致小屋">
            </a>
        </li>
        <li>
            <a href="img/4.jpg" title="高山湖水">
                <img src="img/4.jpg" width="100" alt="高山湖水">
            </a>
        </li>
        <li>
            <a href="img/5.jpg" title="高速公路">
                <img src="img/5.jpg" width="100" alt="高速公路">
            </a>
        </li>
    </ul>
<script>
    window.onload = function () {
        // 1. 获取需要的标签
        var ul = document.getElementById("fj");
        var aList = ul.getElementsByTagName("a");
        // console.log(aList[1]);

        var des = document.getElementById("des");
        var big_img = document.getElementById("big_img");

        // 2.绑定事件
        for(var i=0; i<aList.length; i++){
            aList[i].onclick = function () {

                big_img.src = this.href;
                des.innerHTML = this.title;

               /* console.log(this.href);
                console.log(this.title);*/
                return false;
            }
        }
    }
</script>
</body>
</html>

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