通过事件发射器进行 HTTP 分析

在 HTTP 服务器代码中（例如 server.js）：

const EventEmitter = require('events')
const serverEvents = new EventEmitter()

// Set up an HTTP server
const http = require('http')
const httpServer = http.createServer((request, response) => {
  // Handler the request...
  // Then emit an event about what happened
  serverEvents.emit('request', request.method, request.url)
});

// Expose the event emitter
module.exports = serverEvents

在主管代码中（例如 supervisor.js）：

const server = require('./server.js')
// Since the server exported an event emitter, we can listen to it for changes:
server.on('request', (method, url) => {
  console.log(`Got a request: ${method} ${url}`)
})

每当服务器收到请求时，它都会发出一个名为 request 的事件，主管正在监听该事件，然后主管可以对事件作出反应。