Node.js http.server.listening Property

The http.server.listening is an inbuilt application programming interface of class Server within http module which is used to check if the server is listening for connection or not.

Syntax:

const server.listening

Parameters: It does not accept any argument as a parameter.

Return Value: It does not return any value.

Example 1: Filename: index.js

Javascript

// Node.js program to demonstrate the
// server.listening APi

// Importing http module
const http = require('http');

// Setting up PORT
const PORT = process.env.PORT || 3000;

// Creating http Server
const httpServer = http.createServer(
    function (request, response) {

        // getting the reference of the
        // underlying socket object
        // by using socket API
        const value = response.socket;

        // display result
        // by using end() api
        response.end("socket buffersize : "
            + value.bufferSize, 'utf8', () => {
                console.log("displaying the result...");

                // closing server
                // by using close() api
                httpServer.close(() => {
                    console.log("server is closed")
                })
            });
    });

// Listening to http Server
// by using listen() api
httpServer.listen(PORT, () => {
    console.log("Server is running at port 3000...");
});

// checking if the server is listening or not
if (httpServer.listening)
    console.log("server is listening")
else
    console.log("server is not listening")

Output:

Output: In-Console

server is listening
Server is running at port 3000...
displaying the result...
displaying the result...
server is closed
server is closed

Now run http://localhost:3000/ in the browser.

Output: In-Browser

socket buffersize : 0

Example 2: Filename: index.js

Javascript

// Node.js program to demonstrate the
// server.listening APi

// Importing http module
const http = require('http');

// Request and response handler
const http2Handlers = (request, response) => {

    // getting the reference of the
    // underlying socket object
    // by using socket API
    const value = response.socket;

    // display result
    // by using end() api
    response.end("socket local address : "
        + value.localAddress, 'utf8', () => {
            console.log("displaying the result...");

            // closing server
            // by using close() api
            httpServer.close(() => {
                console.log("server is closed")
            })
        });
};

// Listening to http Server
// by using listen() api
const httpServer = http.createServer(
    http2Handlers).listen(3000, () => {
        console.log("Server is running at port 3000...");
    });

// checking if the server is listening or not
if (httpServer.listening)
    console.log("server is listening")
else
    console.log("server is not listening")

Output:

Output: In-Console

server is listening
Server is running at port 3000...
displaying the result...
displaying the result...
server is closed
server is closed

Now run http://localhost:3000/ in the browser.

Output: In-Browser

socket local address : ::1

Reference: https://nodejs.org/dist/latest-v12.x/docs/api/http.html#http_server_listening