Node.js http.ServerResponse.writableFinished Property

The httpServerResponse.writableFinished is an inbuilt application programming interface of class ServerResponse within http module which is used to check if all the data has been flushed or not.

Syntax:

response.writableFinished

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

Return Value: This property returns true if and only if all the data has been flushed or not.

Example 1: Filename: index.js

Javascript

// Node.js program to demonstrate the
// response.writableFinished 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) {

        // Checking all the data has been flushed
        // or not by using writableFinished API
        const value = response.writableFinished;


        // Display the result
        // by using end() api
        response.end("Data has been flushed : "
            + value, 'utf8', () => {
                console.log("displaying the result...");

                // Closing the server
                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 below command:

node index.js

Console output:

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

Browser Output: Paste the localhost address http://localhost:3000/. In the search bar of the browser.

 Data has been flushed : false

Example 2: Filename: index.js

Javascript

// Node.js program to demonstrate the
// response.writableFinished APi

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

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

    // checking all the data has been flushed or not
    // by using writableFinished API
    const value = response.writableFinished;

    // display result
    // by using end() api
    response.end("Data has been flushed : "
        + value, 'utf8', () => {
            console.log("displaying the result...");

            const value1 = response.writableFinished;
            console.log("Data has been flushed " + value1);
            httpServer.close(() => {
                console.log("server is closed")
            })
        });
};

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

Run the index.js file using the below command:

node index.js

Console Output:

Server is running at port 3000...
displaying the result...
Data has been flushed true

Browser Output: Paste the localhost address http://localhost:3000/. In the search bar of the browser.

Data has been flushed : false

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