라우터 분리 후 ajax 요청이 안먹습니다

선생님 req.body._id 를 적용해도 안됩니다 ㅠㅠ


router.delete("/delete", (req, res)=>{
    req.body._id = parseInt(req.body._id);
    db.collection("todotask").deleteOne(req.body, (err, result)=>{
    })
})




$(".delete").click(function(e){
                let num = e.target.dataset.id;
                let on1 = $(this);
                $.ajax({
                    method : "DELETE",
                    url : "/delete",
                    data : {_id : num }
                }).done(function(result){
                    
                    on1.parent("li").fadeOut()
                    location.reload()
                })
            }) .fail(function(xhr,textStatus,errorThrown){//실패 했을 경우 원인 분석
            console.log(xhr,textStatus,errorThrown)
        }) 

그래도 안됩니다.

routes => todo/js

const express = require("express");

var moment = require('moment-timezone');
moment.tz.setDefault("Asia/Seoul");

const app = express();

const router = express.Router();

router.get("/", (req,res)=>{
    console.log("--------todo------");
    req.app.db.collection("todotask").find().toArray((err, result)=>{
        console.log(result)
        res.render("todo",{todotasks: result})
    })
    
})
//작성
router.post("/write" , (req, res)=>{
    req.app.db.collection('counter').findOne({name: "게시글"}, (err,result)=>{
        var total = result.totalPoint

        console.log(req.body.content) 
        req.app.db.collection("todotask").insertOne({_id : total + 1, content : req.body.content},(err, result)=>{
            req.app.db.collection("counter").updateOne({name:"게시글"},{$inc: {totalPoint : 1}},(err,result)=>{
                if(err){return console.log(err)}
                
            })
            res.redirect("/todo");
    })
    })
    
})

router.get("/edit/:id", (req,res)=>{
    
    req.app.db.collection("todotask").findOne({_id :parseInt(req.params.id)}, (err, result)=>{
        console.log(result)//에러코드 꼭 작성하기
        res.render("edit.ejs",{todotasks: result})
    })
    
})
router.delete("/delete", (req, res)=>{
    req.body._id=parseInt(req.body._id);
    req.app.db.collection("todotask").deleteOne(req.body, (err, result)=>{
        res.send("삭제완료")
    })
    
})

module.exports = router;




routes => index.js

const express = require("express");
const app = express();
const router = express.Router();

//Main 
router.get("/", (req, res)=>{
    res.render("main");
});

//Todo Router
const TodoRouter = require("./todo");

//chat
const ChatRouter = require("./chat/chat")

//game
const GameRouter = require("./game/game")

// Refactoring
router.use("/todo" , TodoRouter);
router.use("/chat", ChatRouter);
router.use("/game", GameRouter)

module.exports = router;

app.js 

//모듈
const express = require("express");
const bodyParser = require("body-parser");
const MongoClient = require("mongodb").MongoClient;
const path = require("path");
const methodOverride = require('method-override')

//서버
const app = express(); //4000: todo
const chatApp = express(); //4001: chat

//채팅 서버 세팅
const http = require("http").createServer(chatApp);
const io = require("socket.io")(http);
module.exports = io;

chatApp.set("view engine", "ejs");
chatApp.engine("html", require("ejs").renderFile);
chatApp.set("views", path.join(__dirname, 'views'));

chatApp.use("/public", express.static(__dirname + '/public'));

//setting -view , static ,body parser
app.set("view engine", "ejs");
app.set("views", path.join(__dirname, 'views'));
app.engine("html", require("ejs").renderFile);

app.use("/public", express.static(__dirname + '/public'));
app.use(methodOverride("_method"))
app.use(express.urlencoded({extended: true}))

//Router Setting
const router = require("./routes/index");
chatApp.use(router);
app.use("/",router)

// Chat Server Open
http.listen(4001, () => {
    console.log("Chat Server listening on port 4001!");
})

//connet to DB
var db;
MongoClient.connect("mongodb+srv://user_06:admin06@cluster0.zgcjhqh.mongodb.net/?retryWrites=true&w=majority",(err,client)=>{
    if(err) return console.log("----error----");
    db = client.db('todoapp')
    app.db = db;

    app.listen("4000", ()=>{
        console.log("listening on 4000")
    })
})

router.put("/edit", (req,res)=>{
    db.collection("todotask").updateOne({_id: parseInt(req.body.id)},{$set : {content : req.body.content}},(err, result)=>{
        if(err){
            console.log("---------puterr-------")
        }
        console.log("수정완료")
        res.redirect("/todo")
    })
})