重复渲染

'use client';
import { io, Socket } from 'socket.io-client';
import { useEffect, useRef, useState } from 'react';
import Monitor from 'utils/monitor';

const OnlineCount = () => {
  const [count, setCount] = useState(0);
  const socket = useRef<WebSocket>();
  async function initSocket() {
    const monitor = new Monitor();
    const userId = await monitor.getVisitor();
    socket.current = new WebSocket(`ws://localhost:3000/v1/ws?userId=$userId`)
    socket.current.onmessage = (event)=>{
      const message = event.data;
      setCount(message)
    }
  }

  useEffect(() => {
    initSocket().then();
    return () => {
      socket.current?.close();
    };
  }, []);
  return (
    <div>
      在线人数 <span className='font-mono'>{count}</span>
    </div>
  );
};
export default OnlineCount;

"use client";
import React, { useEffect, useRef, useState } from 'react';
import Monitor from 'utils/monitor';

const OnlineCount = () => {
  const [count, setCount] = useState(0);
  const socket = useRef<WebSocket | null>(null); // 使用 null 初始化 ref
  const userIdRef = useRef<string | null>(null); // 存储 userId，避免重新渲染时重新获取

  useEffect(() => {
    async function initSocket() {
      if (!userIdRef.current) {
        const monitor = new Monitor();
        userIdRef.current = await monitor.getVisitor();
      }

      if (!socket.current) {
        socket.current = new WebSocket(`ws://localhost:3000/v1/ws?userId=$userIdRef.current`);
        socket.current.onmessage = (event) => {
          const message = event.data;
          setCount(message);
        };
      }
    }

    initSocket();

    return () => {
      if (socket.current) {
        socket.current.close();
        socket.current = null; // 清除连接引用，以便下次重新渲染时重新创建
      }
    };
  }, []); // 空数组表示只在挂载和卸载时执行

  return (
    <div>
      在线人数 <span className='font-mono'>{count}</span>
    </div>
  );
};

export default OnlineCount;