Body 对象代表文档的主体 (HTML body)
<!DOCTYPE html>
<html lang="en" xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta charset="utf-8" />
<title></title>
<script language="javascript">
function dealclick() {
if (b1.innerText == "+") {
list1.style.display = "block";
b1.innerText = "-";
} else {
list1.style.display = "none";
b1.innerText = "+";
}
}
</script>
</head>
<body>
<span id="b1" style="border:thin ridge;cursor:hand"
onclick="dealclick()">-</span>list1<br>
<ul id="list1">
<li>item1</li>
<li>item2</li>
<li>item3</li>
</ul>
list2
</body>
</html>
点击list1后 
原文：http://blog.csdn.net/lindonglian/article/details/45110919