Node.js http.ServerResponse.headersSent Property

Last Updated : 6 Apr, 2023

The httpServerResponse.headersSent is an inbuilt application programming interface of class ServerResponse within the HTTP module which is used to check if the header has been sent or not.

Syntax:

const response.headersSent

Parameters: This property does not accept any arguments as a parameter.

Return Value: This property returns true if and only if headers were sent otherwise false.

Example 1: Filename-index.js

JavaScript 
// Node.js program to demonstrate the
// response.headersSent() method

// 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) {

        // Checking if response header is sent or not
        // by using headersSent method
        const value = response.headersSent;

        // Display result by using end() method
        response.end("Headers have been sent : "
            + value, 'utf8', () => {
                console.log("displaying the result...");

                httpServer.close(() => {
                    console.log("server is closed")
                })
            });
    });

// Listening to http Server
httpServer.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 open your browser and go to http://localhost:3000/, you will see the following output:

Headers have been sent : false

Example 2: Filename-index.js

JavaScript 
// Node.js program to demonstrate the
// response.headersSent() method

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

// Request and response handler
const httpHandlers = (request, response) => {
    // Checking if response header is sent or not
    // by using headersSent method
    const value = response.headersSent;

    // Display result by using end() method
    response.end("Headers have been sent : "
        + value, 'utf8', () => {
            console.log("displaying the result...");

            httpServer.close(() => {
                console.log("server is closed")
            })
        });
};

// Creating http Server
const 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 open your browser and go to http://localhost:3000/, you will see the following output:

Headers have been sent : false

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

Comment

Explore