nodejs request process

Node.js is a server-side JavaScript environment based on an event-driven, non-blocking I/O model that can be used to build efficient and scalable web applications. For the request processing process of Node.js, we need to focus on the implementation of HTTP server and routing respectively.

HTTP Server

The HTTP server module of Node.js The http module provides a createServer() method to create an HTTP server. Whenever a client sends a request to the server, this method will return a Server instance, allowing us to monitor and respond to this instance.

Create HTTP server

const http = require('http');

http.createServer((request, response) => {
  // 请求处理
}).listen(8080);

Request event of HTTP server

Whenever a user sends an HTTP request to the server, the server will automatically generate an http.IncomingMessage object and Trigger the request event, through which we can receive and process HTTP requests. The http.IncomingMessage object also contains all the data carried by the request, such as request path, request method, request header, request body, etc.

const http = require('http');

http.createServer((request, response) => {
  // request事件
  request.on('data', (chunk) => {
    console.log(chunk.toString());
  });

  // 处理请求
  response.writeHead(200, {'Content-Type': 'text/plain'});
  response.end('Hello World
');
}).listen(8080);

Routing

Routing refers to matching the corresponding processor according to the URL request path, thereby achieving different URL access methods and effects.

Routing implementation

We can use a JavaScript object to store the processor methods corresponding to different URLs, and then match the object according to the request path in the request event of the http server, thus Find the corresponding processor method for processing.

const http = require('http');

const urlHandler = {
  '/': function(request, response) {
    response.writeHead(200, {'Content-Type': 'text/plain'});
    response.end('Hello World
');
  },
  '/about': function(request, response) {
    response.writeHead(200, {'Content-Type': 'text/plain'});
    response.end('About page
');
  }
};

http.createServer((request, response) => {
  const path = request.url;

  if (urlHandler[path]) {
    urlHandler[path](request, response);
  } else {
    response.writeHead(404, {'Content-Type': 'text/plain'});
    response.end('404 Not Found
');
  }
}).listen(8080);

The above is a simple implementation of the request processing process of Node.js. Through the collaborative work of the HTTP server and routing module, we can build an efficient and scalable web server to implement various interesting web applications. program.

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