TypeError: Cannot set properties of undefined (setting 'contensts')

안녕하세요 채팅방을 만들었는데 오류가 떠서 문의드립니다

chat.ejs

  <div class="container p-4 detail">

    <div class="row">
      <div class="col-3">
        <ul class="list-group chat-list">
          <% for (var i=0; i < chatlist.length ; i++){ %>
            <button class="room1"data-id="<%= chatlist[i].id %>">
              <h6>
                <%= chatlist[i].title %>
              </h6>
              
            </button>
            <% } %>
        
      </div>
      </div>
 
   

  
  <h1 style="border-bottom:1px solid gray; ">채팅방</h1>

  <div id = "chatting">
        <div class = "content"></div>
    <input id="input1" >

    </div>
    <div id = "sendBox">
      <button id ="room1-send">보내기</button>
</div>
  </div>

  <script src="https://code.jquery.com/jquery-3.4.1.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/socket.io/4.6.0/socket.io.js" integrity="sha512-rwu37NnL8piEGiFhe2c5j4GahN+gFsIn9k/0hkRY44iz0pc81tBNaUN56qF8X4fy+5pgAAgYi2C9FXdetne5sQ==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>
    <script>
      
   var socket = io();
   
  $("#room1-send").click(function () {
    socket.emit("room1-send",$("#input1").val());
    document.getElementById("input1").value = null;
    
  });
  $(".room1").click(function (name) {
    console.log(this.dataset.id);
    socket.emit("joinroom",this.dataset.id);
    socket.emit("room1", "<%= name.id %>");
  });
  
  socket.on("broadcast", function (datalist) {
      
        $(".content").append("<div>" +datalist.name + ":" + datalist.contensts + "</div>");
      });
    </script>




server.js

app.post("/chat", 로그인했니, (req, res) => {
  console.log('req.body.chatroomid=> ' +req.body.chatroomid);
  console.log('req.user.id=> '+req.user._id);
  var save = {
  
    id : ObjectId(ObjectId(req.body.chatroomid)&req.user._id),
    title: req.body.chatroomname,
    member: [ObjectId(req.body.chatroomid), req.user._id],
    date: new Date(),

    
  };
  db.collection("chatroom").find({ member: req.user._id }).toArray().then((result) => {
     //result 채팅리스트
    if(req.body.chatroomid){
      db.collection("chatroom").findOne({member : [ObjectId(req.body.chatroomid),req.user._id]},(error,result2)=>{
       console.log('result2 = > '+result2);
        if(!result2){ 
          db.collection("chatroom")
          .insertOne(save)
          .then((result3) => {   //result2와 비슷  
        res.render("chat.ejs",{chatlist:result,chatting:result3,name:req.user});
      });
        }
        else{
        res.render("chat.ejs",{chatlist:result,chatting:result2,name:req.user});
        }
      })
    } 
    else{
    res.render("chat.ejs",{chatlist:result,chatting:null,name:req.user});
    }
   });
}); // 전체 채팅방
io.on("connection", function (socket) {
  let roomName;
  let Username;
  let datalist ;

  socket.on("room1-send", function (data) {
    console.log("roomName=> " + roomName);
    console.log("보낸사람=>" + Username);
    console.log("메시지=>" + data);

    db.collection("chatroom").updateOne(
      { id: new ObjectId(roomName) },
      {
        $push: { chat: { UserId: Username, contents: data, date: new Date() } },
      },
      { upsert: true },
      (error, result) => {
        datalist.name = Username;
        datalist.contensts = data;
        io.emit("broadcast", datalist);
      }
    );
  });

  
    // 배열로 작성자 내용 일자 추가 만들기
    socket.on("room1", function (name) {
      Username = name;
      console.log("이름" + name);
      db.collection("chatroom").findOne(
        { id: new ObjectId(roomName) },
        (error, result) => {
          if (result.chat) {
            for (var i = 0; i < result.chat.length; i++) {
              datalist = {
                name: result.chat[i].UserId,
                contensts: result.chat[i].contents,
              };
              socket.emit("datalist",{datalist});
              io.to("room1").emit("broadcast", datalist);
            }
          } else {
            
            io.to("room1").emit("broadcast", datalist);
          }
        }
      );
    });
    socket.on("joinroom", function (data) {
      roomName = data;
      console.log("방이름" + data);
      socket.join("room1");
    });
  });



부분입니다. 오류나는 곳이 contensts와 name 에서 오류가 나는데 왜 오류가 나는걸까요ㅠ?