PHP $_POST获取的数据显示 Undefined array key 是什么原因呢

前端代码

chrome.runtime.onMessage.addListener(
    function(request, sender, sendResponse){        
    console.log("收到来自content-script的消息：");
      var pageinfo=new Array(request.msg);
      console.log(pageinfo);
    var rep=$.ajax({
          type:"post",
         url:"http://127.0.0.1/mysqlhelper.php",
         dateType:"json",
         async:true,
         date:{'pageinfo':pageinfo},
             error: function(request) {
                             console.log("Connection error");
                         },
                success: function(res) {
                             console.log(res);
                         }
         });
});

PHP代码

$pageinfo=$_POST['pageinfo'];
$pageinfoarr=explode('@',$pageinfo);
print_r($pageinfoarr);
$servername="127.0.0.1";
$username="root";
$password="Yaoxiuyi@123";
$conn=new mysqli($servername,$username,$password);
if($conn->connect_error){
    die("could not connect:".mysql_error());
}
echo"connect successfully";
$idval=$pageinfoarr[0];
$sql="select * from skulink where id='{idval}'";
$result=$conn->query($sql);
if($result->rows>0){
    while($row=$result->fetch_assos()){
        echo"id:".$row["id"];
    }
    }else{
        echo"0 results";
    }
    


?>

控制台提示
收到来自content-script的消息：
background.js:6 ['636364439288@蓝盘间金主图款@柠檬黄@黑盘@蓝盘银色@黑盘绿圈@蓝盘银带@20144']
Warning: Undefined array key "pageinfo" in D:\webroot\phplearn\mysqlhelper.php on line 5

Array
(
[0] =>
)
connect successfully

Warning: Attempt to read property "rows" on bool in D:\webroot\phplearn\mysqlhelper.php on line 22

0 results

知不知道explode的用法
explode，接收一个字符串，你这个里面是根据 @转换成数组
你前端传的数据是数组类型，explode怎么执行？
把前端第四行 new Array 去掉

打印一下 $_POST['pageinfo'] 的值 ，看一下是什么，看进行处理。

echo $_POST['pageinfo']；

请问 chrome.runtime.onMessage.addListener 是什么？