javascript - 将两个客户端数据保存到一个变量中？

Question

我有两个客户端将连接到我的服务器。我有以下代码来设置服务器，然后客户端将运行命令

在他们的终端上telnet localhost 3000。现在这部分可以工作了

var http = require('http');
var net = require('net')
var listOfClients = []
var server = net.createServer(function(socket) {
  socket.write("Welcome to ROCK PAPER SCISSORS choose from the following \n")
  socket.write("[1] Rock \n")
  socket.write("[2] Paper \n")
  socket.write("[3] Scissors \n")
  listOfClients.push(socket)
  server.getConnections(function(error, count) {
    if (count == 2) {

      let p1 = listOfClients[0].on('data', function(data) {
        return data;

      });

      let p2 = listOfClients[1].on('data', function(data) {
        return data;

      });

      console.log(p1)
      console.log(p2)
    }
  });
});

然后客户选择1或2或3作为石头/剪刀/布我想将他们使用的内容保存在变量中，但是方法

let p1 = listOfClients[0].on('data', function(data) {
  return data;
});

不会将数据保存到变量中并返回很多我不理解的内容。关于如何做到这一点有什么想法吗？我在列表中有套接字，只需要它们将客户端输入保存到变量中。

Answer 1

NodeJS 使用 events 工作。根据文档:

Much of the Node.js core API is built around an idiomatic asynchronous event-driven architecture in which certain kinds of objects (called "emitters") emit named events that cause Function objects ("listeners") to be called.

在您的代码中，listOfClients[0].on('data'... 代码片段实际上是为事件“data”创建监听器。
本质上，您是在告诉代码:嘿，您可以继续听这些内容并在发生时执行某些操作吗？
在您的代码中，您告诉它“当客户端[0]发送一些数据时执行某些操作”。

所以当你写:

const variableName = something.on('someEvent', function(data) {});

变量variableName实际上是接收事件监听器的结果并使用回调作为第二个参数。
让我们编写一个快速函数，其中有一个参数作为回调:

function myFunction(data, callback) {
    callback("This is where you're trying to return the value");

    return 'this is the event listener return';
}

const myVar = myFunction('Anything you please', function(callbackResult) {
    console.log(`This is the callback: ${callbackResult}`);
});

console.log(`This is the var value: ${myVar}`);

运行上述代码将输出:

node v10.15.2 linux/amd64

This is the callback: This is where you're trying to return the value
This is the var value: this is the event listener return

解决您问题的一种方法是将数据分配给事件监听器外部的变量，如下所示:

const storeHere = [];

function myFunction(data, callback) {
    callback("This is where you're trying to return the value");

  return data;
}

const myVar = myFunction('Anything you please', function(callbackResult) {
    storeHere.push(callbackResult); // Store somewhere outside
});

console.log(`This is the externalVar value: ${storeHere}`);
console.log(`This is the var value: ${myVar}`);