Question

有一个API发送一些json数据.nodejs服务器每5秒钟获取一次json数据并通过websocket发送给客户端。如果在clent连接的情况下连接正常，但在客户端断开连接时它不会停止。

代码

io.on('connection', function(client) {  
        var loop=setInterval(()=>{
            console.log('Client connected...');

            fetch('https://www.foo.com/api/v2/searchAssets')
            .then(res => res.json())
            .then(json => 
            {client.emit('news'{json});console.log(json)}),5000);

        })});

io.on('disconnetion',function(){
                clearInterval(loop);
                console.log("disconnected");
            })

OR

除了websocket之外，您还有其他建议将此json数据发送到客户端吗？

提前感谢您的支持

Answer 1

您的问题是范围问题。当您声明loop var时，它在on connection事件的回调中是本地的，在on disconnect事件中不存在。基于如何handle disconnection的文档，您可以像下面这样在连接处理程序内部移动断开处理程序：

io.on('connection', function(client) {
  // Start the interval
  var loop = setInterval(()=>{
    console.log('Client connected...');

    fetch('https://www.foo.com/api/v2/searchAssets')
      .then(res => res.json())
      .then(json => {
        client.emit('news'{json});console.log(json)
      } ,5000);
  });

  // Handles disconnection inside the on connection event
  // Note this is using `client.on`, not `io.on`, and that
  // your original code was missing the "c" in "disconnect"
  client.on('disconnect', () => {
    clearInterval(loop);
    console.log("disconnected");
  });
});

但是我不推荐这种体系结构，因为流数据独立于客户端。数据可以一次获取并全部流化。这是您的操作方法：

var loop

// The function startStreaming starts streaming data to all the users
function startStreaming() {
  loop = setInterval(() => {
    fetch('https://www.foo.com/api/v2/searchAssets')
      .then(res => res.json())
      .then(json => {
        // The emit function of io is used to broadcast a message to
        // all the connected users
        io.emit('news', {json});
        console.log(json);
      } ,5000);
  });
}

// The function stopStreaming stops streaming data to all the users
function stopStreaming() {
  clearInterval(loop);
}

io.on('connection',function() {
  console.log("Client connected");

  // On connection we check if this is the first client to connect
  // If it is, the interval is started
  if (io.sockets.clients().length === 1) {
    startStreaming();
  }
});

io.on('disconnetion',function() {
  console.log("disconnected");

  // On disconnection we check the number of connected users
  // If there is none, the interval is stopped
  if (io.sockets.clients().length === 0) {
    stopStreaming();
  }
});

如何在io套接字中中断setinterval-Node.js

1 个答案: