多个侦听器

Question

服务器部件:

const express = require("express");
const app = express();
const cors = require("cors");
const { UserModel } = require("./models");

app.use(cors());

app.use(express.json());
app.use(express.urlencoded({ extended: true }));

app.options("http://localhost:3000", cors());
const mongoose = require("mongoose");
require("dotenv").config();

const http = require("http").createServer(app);
const io = require("socket.io")(http, {
  cors: {
    origin: ["http://localhost:3002"],
  },
});

http.listen(3001, function () {
  console.log("Server is running");
});

io.on("connection", (socket) => {
  console.log("Socket connected", socket.id);

  socket.on("message:send", (data) => {
    console.log("Пришло в socket.onMessage", data);
    socket.emit("message:fromServer", data);
    // socket.removeListener("message:fromServer");
  });
});

const { userApi } = require("./api/userApi");
app.use("/", userApi);

app.use((err, _, res, __) => {
  return res.status(500).json({
    status: "fail",
    code: 500,
    message: err.message,
  });
});

const { PORT, DB_HOST } = process.env;

const dbConnection = mongoose.connect(DB_HOST, {
  useNewUrlParser: true,
  useFindAndModify: false,
  useCreateIndex: true,
  useUnifiedTopology: true,
});

dbConnection
  .then(() => {
    console.log("DB connect");
    app.listen(PORT || 3000, () => {
      console.log("server running");
    });
  })
  .catch((err) => {
    console.log(err);
  });

客户部分：io.js

import { io } from "socket.io-client";

export const socket = io("http://localhost:3001/");

消息组件

import React from "react";
import { useState } from "react";
// import { useSelector } from "react-redux";
// import { getMessages } from "../../Redux/selectors";
import { socket } from "../helpers/io";
import Message from "../Message/Message";
import { nanoid } from "nanoid";

export default function MessageFlow() {
  const [message, setMessage] = useState([]);

  socket.on("message:fromServer", (data) => {
    console.log("На фронт пришло сообщение: ", data);
    setMessage([...message, data]);
    // setMessage((message) => [...message, data]);
    console.log("Массив сообщений компонента MessageFlow", message);
    console.log(socket.io.engine.transports);
    // socket.off();
    // getEventListeners(socket)['testComplete'][0].remove()
    // socket.removeListener("message:fromServer");
  });

  //   const dispatch = useDispatch();
  // const allMessages = useSelector(getMessages);
  return (
    <div id="mainDiv">
      {message &&
        message.map((i) => {
          // return <Message />;
          return <Message content={i.userId} id={nanoid()} />;
        })}
    </div>
  );
}

信息形式——发布过程的开始

import React, { useState } from "react";
import { useDispatch, useSelector } from "react-redux";
import { sendMessage } from "../../Redux/Chat/Chat-operations";
import { getUser } from "../../Redux/selectors";
import { getToken } from "../../Redux/Auth/Auth-selectors";
import { socket } from "../helpers/io";
import { useEffect } from "react";
import styles from "./MessageForm.module.css";

export default function MessageForm() {
  const [message, setMessage] = useState("");
  const dispatch = useDispatch();
  const userId = useSelector(getUser);
  const currentToken = useSelector(getToken);
  // const getAll = useSelector(allContacts);

  const updateMessage = (evt) => {
    setMessage(evt.target.value);
  };

  const handleSubmit = (e) => {
    e.preventDefault();
    if (message) {
      socket.emit("message:send", { userId: message });
      dispatch(
        sendMessage(
          {
            _id: userId,
            text: message,
          },
          currentToken
        )
      );
    } else {
      alert(`Молчать будем?`);
    }
  };
  return (
    <div className={styles.messageInputContainer}>
      <form>
        <input
          type="text"
          value={message}
          onChange={updateMessage}
          required
          className={styles.messageInput}
          placeholder="Type message to send"
        />
        <button
          type="submit"
          className={styles.messageAddBtn}
          onClick={handleSubmit}
        >
          Send
        </button>
      </form>
    </div>
  );
}

Answer 1

您在每次渲染时添加一个侦听器，您应该使用效果钩子

export default function MessageFlow() {

  useEffect(()=>{ // triggered on component mount or when dependency array change
      const callback = (data) => {
        // what you want to do
      }
      socket.on("message:fromServer", callback);
      return () => { // on unmount, clean your listeners
        socket.removeListener('message:fromServer', callback);
      }
  }, []) // dependency array : list variables used in your listener
  // [...]
}