Ajax使用一+javascript解析Ajax傳回的json字元串

//?抽??锛??瑰?葷?誨???????锛?Ajax?規??ゆ??锛?涓???負login.php??????login.js浠ｇ??
function chklg() {
    if ($('lgname').value == '') {
        alert('杈??ュ???');
        $('lgname').focus();
        return false;
    }
    if ($('lgchk').value != $('chknm').value) {
        alert("楠?璇?????璇?");
        $('lgchk').focus();
        return false;
    }
    
    //?抽??锛?Ajax?峰??user_login_chk.php?版??
    url = 'user_login_chk.php?act=' + (Math.random()) + '&name=' + $('lgname').value + '&pwd=' + $('lgpwd').value;
    xmlhttp.open('get', url, true);

    xmlhttp.send();
    xmlhttp.onreadystatechange = function () {
        if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
            msg = xmlhttp.responseText;
            
            //?抽??锛???val灏?杩?????json瀛?绗?覆msg杞?涓?son锛?骞舵?璇?json,jsonobj.name
            var jsonobj=eval('('+msg+')');      

//????涓???袱?ュ???鋒????      

var jsonobj='';      

eval('jsonobj='+msg+';');          

alert(jsonobj.name);
            $('name').innerHTML = jsonobj;

            if (msg == '1') {
                alert("?誨?????");
                location = "test.php"
            }
            else {
                alert("?誨?澶辮觸");

            }
        }


    }
}
      

涓???負user_login_chk.php浠ｇ??      

<?php
//????娴?璇???session_start();
header('Content-Type:text/html;charset=gb2312');
include_once 'conn/conn.php';
$name = $_GET['name'];
$pwd = $_GET['pwd'];
if(!empty($name) && !empty($pwd)){
    $sql = "select name from tb_member where name = '".$name."'";

    $num = $conne->getRowsNum($sql);
    //$student涓烘?璇??ㄧ??php?扮?锛?
    $student = array("name"=>"lisheng","age"=>"35");
    $studentJson = json_encode($student);

    if($num == 0 || $num == '' ){
        $reback = $studentJson;
    }else{
        $reback = $studentJson;
    }
}
echo $reback;

?>