jquery选择器

<!DOCTYPE HTML>
<html lang="en-US">
<head>
    <meta charset="UTF-8">
    <title></title>
    <script src="../jquery.js" type="text/javascript"></script>
    <script type="text/javascript">
        $(function(){
            $("input[type='button']").click(function(){
                var i = 0;
                $("input[type='text']").each(function(){
                    i += parseInt($(this).val());
                });
                $('label').text(i);
            });
            $('input:lt(2)')
                .add('label')
                .css('border', 'none')
                .css('borderBottom', 'solid 1px navy')
                .css({'width':'30px'});
                
        });
        
    </script>
</head>
<body>
    <input type="text" value="1" />+
    <input type="text" value="2" />
    <input type="button" value="=" />
    <label>&nbsp;</label>
</body>
</html>