Node.js http.server.listen() Method

12 Jan, 2021
The http.server.listen() is an inbuilt application programming interface of class Server within the http module which is used to start the server from accepting new connections.
Syntax:
const server.listen(options[, callback])
Parameters: This method accepts the following two parameters:
option: It can be the port, host, path, backlog, exclusive, readableAll, writableAll, ipv6Only, etc depending upon user need.
callback: It is an optional parameter, it is the callback function that is passed as a parameter.
Return Value: This method returns nothing but a callback function.
Example 1: Filename-index.js
Javascript
// Node.js program to demonstrate the  // server.listen() method  // Importing http module var http = require('http');  // Setting up PORT const PORT = process.env.PORT || 3000;  // Creating http Server var httpServer = http.createServer(    function (request, response) {      // Getting the reference of the    // underlying socket object    // by using socket method    const value = response.socket;      // Display result    // by using end() method    response.end("socket buffersize : "         + value.bufferSize, 'utf8', () => {            console.log("displaying the result...");              // Closing server             // by using close() method            httpServer.close(() => {                console.log("server is closed")            })        });});  // Listening to http Server // by using listen() methodhttpServer.listen(PORT, () => {    console.log("Server is running at port 3000...");});
Run the index.js file using the following command:
node index.js
Output:
Server is running at port 3000...
displaying the result...
server is closed
Now run http://localhost:3000/ in the browser and you will see the following output on screen:
socket buffersize : 0
Example 2: Filename-index.js
Javascript
// Node.js program to demonstrate the  // server.listen() method  // Importing http module var http = require('http');  // Request and response handler const httpHandlers = (request, response) => {      // Getting the reference of the    // underlying socket object    // by using socket method    const value = response.socket;      // Display result by using end() method    response.end("socket local address : "         + value.localAddress, 'utf8', () => {            console.log("displaying the result...");              // Closing server by using close() method            httpServer.close(() => {                console.log("server is closed")            })        });};  // Listening to http Server // by using listen() methodvar httpServer = http.createServer(    httpHandlers).listen(3000, () => {    console.log("Server is running at port 3000...");});
Run the index.js file using the following command:
node index.js
Output:
Server is running at port 3000...
displaying the result...
server is closed
Now run http://localhost:3000/ in the browser and you will see the following output on screen:
socket local address : ::1
Reference: https://nodejs.org/dist/latest-v12.x/docs/api/http.html#http_server_listen
Node.js-Methods
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