HTML DOM部分---document对象；

<style type="text/css">
#d3{ color:red}
</style>

</head>

<body>

<div id="d1" cs="ceshi"><span>document对象</span></div>

<div class="d">111</div>
<span class="d">222</span>

<input type="text" name="aa" id="b1" value="biaodan" />
<input type="text" name="aa" />

<div id="d3" style="100px; height:100px; background-color:#636">111</div>

<input type="button" value="获取" onclick="showa()" />
<input type="button" value="设置" onclick="set()" />

</body>

<script type="text/javascript">

//找元素
//1.根据id找
//var d1 = document.getElementById("d1");
//alert(d1);

//2.根据class找
//var d2 = document.getElementsByClassName("d");
//alert(d2[1]);

//3.根据标签名找
//var d3 = document.getElementsByTagName("div");
//alert(d3[0]);

//4.根据name找
//var d4 = document.getElementsByName("aa");
//alert(d4[0]);

//操作元素
//操作内容
//非表单元素
//var d1 = document.getElementById("d1");
//1.获取文本
//alert(d1.innerText);
//2.设置文本
//d1.innerText = "hello";
//3.获取html代码
//alert(d1.innerHTML);
//4.设置html代码
//d1.innerHTML = "<b>加粗文字</b>";

//表单元素
//var b1 = document.getElementById("b1");
//1.赋值
//b1.value = "ceshi";
//2.获取值
//alert(b1.value);

//操作属性
//1.添加属性
//var d1 = document.getElementById("d1");
//d1.setAttribute("bs","1");
//2.获取属性
//alert(d1.getAttribute("cs"));
//3.移除属性
//d1.removeAttribute("cs");

//操作样式
/*function showa()
{
//1.获取样式,只能获取内联样式
var d3 = document.getElementById("d3");
alert(d3.style.color);
}
function set()
{
var d3 = document.getElementById("d3");
//2.设置样式
d3.style.backgroundColor = "red";
}*/

<div onclick=""></div> 鼠标单击
<div ondblclick=""></div> 鼠标双击
<div onkeydown=""></div> 键敲下
<div onkeypress=""></div> 键敲击
<div onkeyup=""></div> 键敲击后抬起
<div onmousedown=""></div> 鼠标点击下
<div onmousemove=""></div> 鼠标移动
<div onmouseout=""></div> 鼠标离开
<div onmouseover=""></div> 鼠标悬浮上边
<div onmouseup=""></div> 鼠标点击抬起

例一；

<body>

<input type="checkbox" id="ck" onclick="xiugai()" />同意
<input type="button" value="注册" id="btn" disabled="disabled" />

</body>
<script type="text/javascript">

function xiugai()
{
    //找到复选框
    var ck = document.getElementById("ck");
    //找到按钮
    var btn = document.getElementById("btn");
    
    //判断复选框的选中状态
    if(ck.checked)
    {
        //移除按钮的不可用属性
        btn.removeAttribute("disabled");
    }
    else
    {
        //设置不可用属性
        btn.setAttribute("disabled","disabled");
    }
}


</script>

例2；

<style type="text/css">
#caidan{
    width:500px; height:35px; border:1px solid #60F;
    
    }

.xiang{
    width:100px; 
    height:35px;
    text-align:center;
    line-height:35px;
    vertical-align:middle;
    float:left;
    }

</style>
</head>

<body>

<div id="caidan">
    <div class="xiang" onmouseover="huan(this)" >首页</div>
    <div class="xiang" onmouseover="huan(this)" >产品中心</div>
    <div class="xiang" onmouseover="huan(this)" >服务中心</div>
    <div class="xiang" onmouseover="huan(this)" >联系我们</div>
</div>


</body>
<script type="text/javascript">
function huan(a)
{
    //将所有的项恢复原样式
    var d = document.getElementsByClassName("xiang");
    for(var i=0;i<d.length;i++)
    {
        d[i].style.backgroundColor="white";
        d[i].style.color = "black";
    }
    
    //换该元素的样式
    a.style.backgroundColor = "red";
    a.style.color = "white";
}
/*function huifu(a)
{
    a.style.backgroundColor = "white";
    a.style.color = "black";
}*/
</script>

例3：

<body>


<div>
    <span id="daojishi">10</span>
    <input disabled="disabled" type="button" value="注册" id="anniu" />
</div>


</body>

<script type="text/javascript">
    
    
    window.setTimeout("daojishi()",1000);
    
    //功能：倒计时减1
    function daojishi()
    {
        //找到span
        var s = document.getElementById("daojishi");
        
        //判断
        if(parseInt(s.innerHTML)<=0)
        {
            document.getElementById("anniu").removeAttribute("disabled");
        }
        else
        {
        //获取内容，减1之后再交给span
        s.innerHTML = parseInt(s.innerHTML)-1;
        
        //每隔一秒调一次该方法
        window.setTimeout("daojishi()",1000);
        }        
    }
    
</script>