DOM学习之图片库切换效果

2018-07-23 06:15:55来源：博客园阅读 ()

addloadevent(prepareplaceholder())
addloadevent(prepareGallery())
//页面加载完时执行函数
function addloadevent(func) { //参数放入你界面加载完要执行的函数
    var oldonload = window.onload;
    if (typeof window.onload != 'function') {
        window.onload = func;
    } else {
        oldonload();
        func();
    }
}
// 向后插入元素方法
function insertAfter(ent,hou) { //第一个参数你要出入的节点，第二参数你要插入谁的后面
    var parer = hou.parentNode; //获取他的父级判断所选的元素是否是最后一个
    if (parer.lastChild == hou) {
        parer.appendChild(ent); //如果是最后一个直接执行appendChild插入到后面
    } else {
        parer.insertBefore(ent, hou.nextSibling); //如果不是则插入到父级的同级的前面 

    }
}
//插入img 和 p节点设置属性
function prepareplaceholder() {
    if (!document.createElement) return false;
    if (!document.createTextNode) return false;
    if (!document.getElementById) return false;
    if (!document.getElementById("imagegallery")) return false;
    //创建一个img标签设置属性
    var placeholder = document.createElement("img");
    placeholder.setAttribute("id", "placeholder");
    placeholder.setAttribute("src", "img/200u0l000000d8n8xB0E3_R_550_412.jpg");
    placeholder.setAttribute("alt", "第一张图片");
    //创建一个p标签给他设置属性
    var description = document.createElement("p");
    description.setAttribute("id", "description");
    var desctext = document.createTextNode("第一张图片");
    description.appendChild(desctext);
    // 将创建好的标签插入HTML文档中
    var gallery = document.getElementById("imagegallery");
    insertAfter(placeholder, gallery);
    insertAfter(description, placeholder);
}
//给a标签绑定点击事件
function prepareGallery() {
    if (!document.getElementsByTagName) return false;
    if (!document.getElementById) return false;
    if (!document.getElementById("imagegallery")) return false;

    var galley = document.getElementById("imagegallery");
    var links = galley.getElementsByTagName("a");

    for (var i = 0; i < links.length; i++) {
        links[i].onclick = function() {
            return showPic(this);
        }
        links[i].onkeypress = links[i].onclick;
    }
}
//点击后执行的函数
function showPic(whichpic) {
    if (!document.getElementById("placeholder")) return true;

    var source = whichpic.getAttribute("href");

    var placeholder = document.getElementById("placeholder");
    placeholder.setAttribute("src",source);

    if (!document.getElementById("placeholder")) return false;

    if (whichpic.getAttribute("title")) {
        var text = whichpic.getAttribute("title");
    } else {
        text = "";
    }
    var description = document.getElementById("description");
    //判断P标签中的节点类型 3为文本类型#text 设置文本
    if (description.firstChild.nodeType == 3) {
        description.firstChild.nodeValue = text;
    }
    return false;
}

HTML代码

<!DOCTYPE html>
<html>

<head>
    <title>图片库效果</title>
    <link rel="stylesheet" type="text/css" href="css/style.css">
</head>

<body>
    <h1>点击图片效果</h1>
    <ul id="imagegallery">
        <li>
            <a href="img/200u0l000000d8n8xB0E3_R_550_412.jpg" title="第一张图">
                <img src="img/200u0l000000d8n8xB0E3_R_550_412.jpg" alt="fffd">
            </a>
        </li>
        <li>
            <a href="img/20080o000000f95k889B2_R_550_412.jpg" title="第二张图">
                <img src="img/20080o000000f95k889B2_R_550_412.jpg" alt="bbf">
            </a>
        </li>
        <li>
            <a href="img/200h0d0000006tsrr8195_R_550_412.jpg" title="第三张图">
                <img src="img/200h0d0000006tsrr8195_R_550_412.jpg" alt="fff ">
            </a>
        </li>
        <li>
            <a href="img/4b9185dbdb71431ab128af73baf22ce1_R_550_412.jpg" title="第四张图">
                <img src="img/4b9185dbdb71431ab128af73baf22ce1_R_550_412.jpg" alt="fff ">
            </a>
        </li>
    </ul>
    <script type="text/javascript" src="js/script.js"></script>
</body>

</html>

CSS代码

h1{
    width: 290px;
    margin: 0 auto;
    height: 60px;
    line-height: 60px;
    text-align: center;
    color: #13af13;
}
#imagegallery{
    width: 290px;
    height: 50px;
    margin: 0 auto;
    padding: 5px 0 0 0;
    background-color: #e2e2e2;
}
#imagegallery li{
    float: left;
    width: 60px;
    list-style: none;
    margin-left: 10px;
}
#imagegallery img ,#imagegallery a{
    text-decoration: none;
    font-style: normal;
    display: block;
    width: 100%;
}
#placeholder{
    display: block;
    border: 4px solid #13af13;
    width: 282px;
    margin: 0 auto;
}
p{
    text-align: center;
}