初学JS之实现选项卡切换

实现思路：

1、首先获取id元素。
2、for循环历遍按钮元素添加onclick事件。
3、排他思想，点击按钮时设置所有选项卡按钮样式为空，利用this关键字指定当前选项卡获得高亮样式。
4、下面的多个div内容块以此类推。
源代码：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>简单的选项卡切换（仿Hao123导航）</title>
</head>
<style>
    * {
        margin: 0;
        padding: 0;
    }
    .box {
         278px;
        margin: 0 auto;
        margin-top: 100px;
        background-color: #F7F7F8;
        overflow: hidden;
    }
    .btn button {
        outline:none;
        color: #616161;
        font:14px/100% arial,"Hiragino Sans GB","Hiragino Sans GB W3",5b8b4f53;
        border: none;
        height: 34px;
         51px;
        background-color: #F7F7F8;
        float: left;
        cursor: pointer;
    }
    .box .btn i {
        height: 16px;
        border-left: 1px solid #EAEAEA;
        margin-top: 9px;
        float: left;
        _font-size: 0px;
    }
    .box .btn button:hover {
        color: #0AA770;
    }
    .box .btn s {
        cursor: pointer;
        text-decoration: none;
        font:14px/34px arial,"Hiragino Sans GB","Hiragino Sans GB W3",5b8b4f53;
    }
    #box1 #btns .clickbtn {
        border-top: 1px solid #0AA770;
        color: #0AA770;
    }
    .bottom {
        display: none;
        position: absolute;
         278px;
        height: 110px;
        color: #fff;
        text-align: center;
        font:14px/100% arial,"Hiragino Sans GB","Hiragino Sans GB W3",5b8b4f53;
    }
    .bottom a {
        color: #fff;
        position: relative;
        top: -20px;
        left: 0px;
        text-decoration: none;
    }
    .bottom a:hover {
        text-decoration: underline;
    }
</style>
<script>
    window.onload = function(){
        var btns = document.getElementById("btns").getElementsByTagName("button");
        var divs = document.getElementById("bottomdivs").getElementsByTagName("div");
        btns[0].className = "clickbtn";
            for(var i = 0;i<btns.length;i++){
                btns[i].index = i;
                btns[i].onclick = function(){
                    //alert(this.index);
                    for(var j = 0;j<btns.length;j++){
                        btns[j].className = "";
                    }
                    this.className = "clickbtn";
                    for(var b = 0;b<btns.length;b++){
                        divs[b].style.display = "none";
                    }
                    divs[this.index].style.display = "block";

                }
        }
    }
</script>
<body>
<div class="box" id="box1">
    <div class="btn" id="btns">
        <button>推介</button>
        <i></i>
        <button>社会</button>
        <i></i>
        <button>娱乐</button>
        <i></i>
        <button>军事</button>
        <i></i>
        <button>体育</button>
        <s>+</s>
    </div>
    <div id="bottomdivs">
        <div class="bottom" style="display: block">
            <img src="images/01.jpg" alt="">
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        <div class="bottom">
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        <div class="bottom">
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        </div>
    </div>
</div>
</body>
</html>