window.document 对象

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<script type="text/javascript">

function getById(id)
{
//根据id查找

var aa = document.getElementById(id);

aa.style.backgroundColor="#FFF";

alert(aa);
/*

alert("innerHTML = " + aa.innerHTML);
alert("outerHTML" + aa.outerHTML);
alert("innerText" + aa.innerText);

aa.innerText = "";*/

}

function getByName(name)
{
//根据id查找
//var aa = document.getElementById(id);

var aa = document.getElementsByName(name);

alert(aa);

if (aa.length > 0)
{
	alert(aa[0].innerText);
}

/*alert("innerHTML = " + aa.innerHTML);
alert("outerHTML" + aa.outerHTML);
alert("innerText" + aa.innerText);

aa.innerText = "";*/
}

function getByTagName(name)
{
var aa = document.getElementsByTagName(name);

alert(aa);

if (aa.length > 0)
{
	for (var i = 0; i < aa.length; i++)
	alert(aa[i].innerText);
}

/*alert("innerHTML = " + aa.innerHTML);
alert("outerHTML" + aa.outerHTML);
alert("innerText" + aa.innerText);

aa.innerText = "";*/
}

function getByClassName(name)
{
var aa = document.getElementsByClassName(name);

alert(aa);

if (aa.length > 0)
{
	for (var i = 0; i < aa.length; i++)
	alert(aa[i].innerText);
}

/*alert("innerHTML = " + aa.innerHTML);
alert("outerHTML" + aa.outerHTML);
alert("innerText" + aa.innerText);

aa.innerText = "";*/
}

function getByForm()
{
	try
	{
	var aa = document.myForm.f6;

	alert(aa.value);

	aa.value = "新的内容";

	aa.setAttribute("newvalue", "新属性值");

	var bb = aa.getAttribute("daan")

	alert(bb);

	aa.removeAttribute("newvalue");

	bb = aa.getAttribute("newvalue");

	alert(bb);
	}
	catch(ex)
	{
		alert(ex);
	}
}

</script>
</head>

<body>

<div style="background-color:#F00; height:100px;" id="a" name="b" ><b>这是另一个元素</b></div>
<div class="c" id="ab"><b>这是一个元素</b></div>

<form  name="myForm" action="#" method="get" >

<br />

<input id="f1" type="button" onclick='getById("a");' value="根据ID查找元素" />

<br />

<input id="f2"  type="button" onclick='getByName("b");' value="根据Name查找元素" />

<br />

<input id="f3"  type="button" onclick='getByTagName("div");' value="根据TagName查找元素" />

<br />

<input id="f4"  type="button" onclick='getByClassName("c");' value="根据ClassName查找元素" />

<br />
<input id="f6" daan="1921年" type="text" width="30" value="内容" />

</form>

<br />

<input id="f5"  type="button" onclick='getByForm();' value="查找表单元素" />

</body>
</html>