node.js - 回调函数的变量范围

Question

我正在使用 TLS 模块在 node.js 中制作一个简单的服务器。到目前为止一切顺利，客户端能够连接、发送数据和断开与服务器的连接。但是，我想在与服务器断开连接时打印客户端的 IP 地址。就目前而言，我可以从事件回调函数之外打印客户端的 IP 地址，但我不能在回调函数中这样做（检查on('end)）。

var tls = require('tls');
var fs = require('fs');

var server = tls.createServer({
    key: fs.readFileSync('server-key.pem'),
    cert: fs.readFileSync('server-cert.pem'),
}, function(cleartextStream) {
    cleartextStream.setEncoding('utf8');

    /*
     * Error receiving data.
     */
    cleartextStream.on('error', function (exception) {

    });

    /*
     * Signal that it is safe to write again.
     */
    cleartextStream.on('drain', function () {

    });

    /*
     * New data received.
     */
    cleartextStream.on('data', function (data) {
        console.log('New data: '+data);
    });

    /*
     * Remote client disconnected.
     */
    console.log(cleartextStream.remoteAddress); // This prints the IP address correctly.

    cleartextStream.on('end', function () {
        console.log(cleartextStream.remoteAddress); // This prints undefined.
    });

    /*
     * Server is shutting down.
     */
    cleartextStream.on('close', function () {

    });
});

server.listen(8000, function() {
  console.log('Server listening.');
});

Answer 1

看起来在事件触发之前删除了 的remoteAddress属性。所以捕获远程地址，以便它在您的事件回调中仍然可用：cleartextStream'end''end'

var remoteAddress = cleartextStream.remoteAddress;
cleartextStream.on('end', function () {
    console.log(remoteAddress);
});