json数据返回

<script type="text/javascript">
function xmlpage(){
    var xhr=new XMLHttpRequest();
    xhr.onreadystatechange=function(){
        if(xhr.readyState===4){
            eval("var obj="+xhr.responseText);
            var str="地址"+obj.weatherinfo.city+"温度"+obj.weatherinfo.temp+"风向"+obj.weatherinfo.WD;
            document.getElementById("tq").innerHTML=str;
            }
        }
    xhr.open("GET","/6.php");
    xhr.send(null);
    }
window.onload=function(){
    xmlpage();};
</script>
<div id="tq"></div>