How nodejs accepts requests

Node.js is a JavaScript runtime environment based on the Chrome V8 engine that can help developers perform efficient server-side programming. In Node.js, accepting user requests is a very critical task as they form the basis of server-side applications. This article will show you how to accept requests in Node.js.

Node.js provides an HTTP module that can be used to create servers and accept requests. By using this module, you can easily create an HTTP server and handle HTTP requests in it. The following are the basic steps to create an HTTP server in Node.js:

First, you need to introduce the HTTP module:

const http = require('http');

Second, create the server in code:

const server = http.createServer();

Next , listen for requests on the server:

server.on('request', (req, res) => {
  // 处理请求
});

The above code will create an HTTP server named server and detect all requests from the client.

In the request processing function, you can obtain the request method, URL, request header and request body, and send a response to the client. The following code demonstrates how to obtain some information about an HTTP request and process the response:

server.on('request', (req, res) => {
  const { method, url, headers } = req;
  const body = [];
  req.on('data', (chunk) => {
    body.push(chunk);
  }).on('end', () => {
    const data = Buffer.concat(body).toString();
    res.statusCode = 200,
    res.setHeader('Content-Type', 'text/plain');
    res.end('Hello World');
  });
});

In the above code, the request method, URL and request headers are first obtained. Then use the req.on() method to get the data in the request body.

Finally, use res.statusCode to set the status code of the response, the res.setHeader() method to set the response header, and use res.end() to send the response body.

At this point, we have learned how to create a server, listen for requests, and get requests and send responses. However, in practice, handling a request involves more than just sending some simple text response. Typically, you need to get parameters or routes from the URL, get data from the database, and send responses to the client HTML, JSON, XML, or files, etc.

In order to handle rich requests, we can use frameworks such as Express, Koa, Hapi, etc., and refer to their documentation to understand how to use these frameworks to handle requests.

While the way requests are handled may vary depending on the needs of the application, the basic tools provided by Node.js already make it easy to accept and handle user requests.

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