document.forms 可以获取表单数组
<html>
<head>
<title>00</title>
<script type="text/javascript" charset="utf-8">
function operatorForm(){
var myform=document.forms[0];
//alert(myform.action);
//alert(myform.method);
//alert(myform.target);
//myform.submit();
myform.reset();
}
</script>
</head>
<body>
<form id="myform" action="http://www.baidu.com" method="get" target="_self">
<input name="username" type="text" value="chenhao"/><br/>
<input name="password" type="text" value="123456"/><br/>
<select name="city">
<option value="shanghai">上海</option>
<option value="nanjing" selected="selected">南京</option>
</select><br/>
<input type="button" value="获取表单内第一个控件"
onclick="alert(document.getElementById('myform').elements[0].value)"/>
<input type="button" value="获取表单内第二个控件"
onclick="alert(document.getElementById('myform').elements['password'].value)"/>
<input type="button" value="获取表单内第三个控件"
onclick="alert(document.getElementById('myform').city.value)"/>
<input type="button" value="操作表单"
onclick="operatorForm()"/>
</form>
</body>
</html>