ajax获取text的值为空咋回事呢？<input id="birds">取出的值是空 _Ajax

ajax获取text的值为空怎么回事呢？<input id="birds">取出的值是空 - Web 开发 / Ajax
HTML code
<!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=gb2312" />
<title></title>
<script src="./jQuery UI Autocomplete - Remote datasource_files/jquery-1.5.1.js"></script>
<script src="./jQuery UI Autocomplete - Remote datasource_files/jquery.ui.core.js"></script>
<script src="./jQuery UI Autocomplete - Remote datasource_files/jquery.ui.widget.js"></script>
<script src="./jQuery UI Autocomplete - Remote datasource_files/jquery.ui.position.js"></script>
<script src="./jQuery UI Autocomplete - Remote datasource_files/jquery.ui.autocomplete.js"></script>
<META HTTP-EQUIV="Pragma" CONTENT="no-cache">
<META HTTP-EQUIV="Cache-Control" CONTENT="no-cache">
<META HTTP-EQUIV="Expires" CONTENT="0">
<link rel="stylesheet" href="demos.css">
<link rel="stylesheet" href="jquery.ui.all.css">
<style>
    .ui-autocomplete-loading { background: white url('images/ui-anim_basic_16x16.gif') right center no-repeat; }
</style>
<!--<script type="text/javascript">
    $(function () {
    $('input:text:first').focus();
    var $inp = $(':input');
    $inp.bind('keydown', function (e) {
        
        var key = e.which;
        //window.alert(e.ctrlKey);
        if (key == 13||(e.ctrlKey&&key == 13)) {
            e.preventDefault();
            if(this.type=="submit")
            {
                document.forms[0].submit();
            }
            var nxtIdx = $inp.index(this) + 1;
            $(":input:eq(" + nxtIdx + ")").focus();
        }
    });
});
</script>-->
 <script type="text/javascript">
$(function()
{
    $("#myform input:text").keypress(function(e)
    {
        if (e.which == 13)//判断所按是否回车键
        {
            var inputs = $("#myform").find(":text");//获取表单中的所有输入框
            var idx = inputs.index(this);//获取当前焦点输入框所处的位置
            
            if (idx == inputs.length - 1)// 判断是否是最后一个输入框
            {
               // if (confirm("最后一个输入框已经输入,是否提交?"))   //用户确认
                    $("#myform").submit();    //提交表单
            }
            else
            {
                inputs[idx + 1].focus();//设置焦点
                inputs[idx + 1].select();//选中文字
            }

            return false;//取消默认的提交行为
        }
    });
});
</script>
<script>
    $(function() {
        function log( message ) {
            $( "<div/>" ).text( message ).prependTo( "#log" );
            $( "#log" ).attr( "scrollTop", 0 );
        }
        
        var textval = $("#birds").attr("value");// 
        alert(textval);
        $( "#birds" ).autocomplete({
            //source: "search.php",
            source: 'search.php?ts='+new Date().getTime()+'&k='+encodeURIComponent(textval),
            //source: 'search.php?ts='+new Date().getTime()+'&k='+encodeURIComponent(ui.item.value),
            minLength: 2,
            select: function( event, ui ) {
                log( ui.item ?
                    "Selected: " + ui.item.value + " aka " + ui.item.id :
                    "Nothing selected, input was " + this.value );
            }
        });
        //$( "#birds1" ).autocomplete({
        //    source: "search.php",
        //    minLength: 2,
        //    select: function( event, ui ) {
        //        log( ui.item ?
        //            "Selected: " + ui.item.value + " aka " + ui.item.id :
        //            "Nothing selected, input was " + this.value );
        //    }
        //});
    });
</script>
</head>

<body>
<table width="736" height="127" border="1">
<form method="post" action="" id="myform">
<div class="demo">
  <tr>
    <td colspan="4">方剂类型：</td>
  </tr>
  <tr>
    <td colspan="2">
        <input type="radio" name="radiobutton" value="radiobutton" />茶剂
    </td>
    <td width="107">
        <input type="radio" name="radiobutton" value="radiobutton" />药剂
    </td>
    <td width="437">
        <input type="radio" name="radiobutton" value="radiobutton" />汤剂
    </td>
  </tr>
  <tr>
    <td colspan="4">查询药剂：</td>
  </tr>
  <tr>
    <td width="168">
        <div class="ui-widget">
            <label for="birds">Birds: </label>
            <input id="birds">
        </div>
      </label>
    </td>
    <td colspan="2">
        <input type="text" name="textfield2" size="6" />克
    </td>
    <td>
        <input name="Input" type="button" value="确认" />
    </td>
  </tr>
  </form>
  </div>
  
</table>
<div class="ui-widget" style="margin-top:2em; font-family:Arial">
Result:
<div id="log" style="height: 200px; width: 300px; overflow: auto;" class="ui-widget-content"></div>
</div>
</body>
</html>