index.html
<!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>表单选择器</title>
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript" src="demo.js"></script>
<link type="text/css" rel="stylesheet" href="style.css" />
</head>
<body>
<form>
<input type="hidden" name="id" value="123" />
<input type="text" disabled="disabled" name="user" value="123" />
<input type="password" name="pass" value="456" />
<textarea></textarea>
<select name="city">
<!--option value="123">123</option-->
<option>1</option>
<option>2</option>
<option>3</option>
</select>
<button></button>
<input type="radio" name="sex" value="男" checked="checked" />男
<input type="radio" name="sex" value="女" />女
</form>
</body>
</html>
demo.js
$(function(){
//alert($('input').size());
//alert($('input').val());
//alert($('input').eq(1).val()); //这种写法语义不清晰
//alert($('input[type=password]').val()); //语义清晰一点
//alert($('input[name=user]').val());//推荐
//alert($('input[type=password][name=pass]').val());
//alert($('input').size());
//alert($(':input').size());
//alert($(':input[name=city]').val());
//alert($(':text').size());
//alert($(':password').size());
//alert($(':radio').size());
//alert($(':radio[name=sex]').eq(1).size());
//alert($(':radio[name=sex]').last().size());
//alert($('form :hidden').size());
//alert($('form :enabled').size());
//alert($('form :disabled').size());
//alert($('form :checked').size());
//alert($('form :selected').get(0));
alert($('form :selected').size());
});