<script type="text/javascript">
var xmlHttp;
function a(id){
      var num=document.getElementById("num"+id).value;
      var numbers=document.getElementById("numbers"+id).innerHTML;
      alert(num+"num"+numbers);
      try{
            xmlHttp=new XMLHttpRequest();
      }catch (e){
      try{
            xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
      }catch (e){
      try{
            xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
      }catch (e){
      alert("您的浏览器不支持AJAX！");
return false;}}
}
alert(num+"num"+numbers);
xmlHttp.onreadystatechange=callback;
if(num<numbers){
      var url="../updatecartnumbers?id="+id+"&num="+num;
      alert(url);
      xmlHttp.open("post",url,true);
      xmlHttp.send(null);
}else{
alert("请重新填写数量！");}
}
function callback(){
      alert(xmlHttp.readyState);
      if(xmlHttp.readyState==4){
            alert(xmlHttp.status);
            if(xmlHttp.status==200){
                  var txt=xmlHttp.responseText;
                  alert(txt);
                  var s= txt.split(",");
                  var id=s[2];
                  document.getElementById("total").innerHTML=s[0];
                  document.getElementById("numbers"+id).innerHTML=s[3];
                  document.getElementById("smallnum"+id).innerHTML=s[1];
            }
      }
}
</script>