Skip to main content

Utilizing HTTP/2 Push for Faster Page Load in Node.js

HTTP/2 has several advantages over HTTP/1 that I've mention in my earlier post. In this post, I want to show how push-request can be performed using Node.js to create an HTTP/2 server. Push request is used to push static files such as scripts and styles so that the client can consume those static files as soon as possible without the need to request them first.

In this example, several built-in Node modules are required and an external module for ease of content-type setting named mime. Let's install it first.

npm init
npm i --save mime

HTTP/2 encodes all headers of a request and it presents several new headers for identifying a request such as :method and :path. For more clarity, I call some constants related to the HTTP/2 header from the http2.constants property. Let's create the server.js file.

const http2 = require('http2');
const { 
} = http2.constants;

const mime = require('mime');
const path = require('path');
const fs = require('fs');
const fsp = require('fs/promises');
const { O_RDONLY } = fs.constants;

Currently, most browsers require TLS encrypted communication for HTTP/2 so that for this demo, we need to generate a self-signed certificate and include the certificate as the server parameter.

const serverPort = 3000;
const publicLocation = 'public'; // directory to store static files
const serverOptions = {
  key: fs.readFileSync('./your-selfsigned-key.pem'),
  cert: fs.readFileSync('./your-selfsigned-cert.pem')

We need to create a public directory. Then, create several static files including index.html, app.js, and style.css inside the directory. We can write any methods or declarations inside those files for demo purposes. The index.html file should include app.js and style.css on the head or body.

In server.js, we create a function that will handle file sending through the HTTP/2 stream. In Node.js, the stream is an instance of the http2.ServerHttp2Stream object.

function sendFile(stream, fileLocation) {
  let fileHandle;, O_RDONLY)
    .then((fh) => {
      fileHandle = fh;
      return fileHandle.stat();
    .then((stats) => {
      // setup file sending header
      const headers = {
        [HTTP2_HEADER_CONTENT_LENGTH]: stats.size,
        [HTTP2_HEADER_LAST_MODIFIED]: stats.mtime.toUTCString(),
        [HTTP2_HEADER_CONTENT_TYPE]: mime.getType(fileLocation)

      // close the file in 'close' event of the stream
      stream.on('close', () => {

      // send response with file descriptor
      stream.respondWithFD(fileHandle.fd, headers);
    .catch((reason) => {


Last, we define an HTTP/2 server object that will handle file requests. For this demo, the server only accepts any request to index.html file. Other requests will be responded with a plain text message.

const server = http2.createSecureServer(serverOptions);

server.on('stream', (stream, headers) => {

  // get some headers
  const method = headers[HTTP2_HEADER_METHOD].toLowerCase();
  const url = new URL(headers[HTTP2_HEADER_PATH], 'https://' + headers[HTTP2_HEADER_AUTHORITY]);
  const pathname = url.pathname.replace(/^\/+|\/+$/g, '');

  // handle root or index.html file request
  if (pathname==='' || pathname==='index.html') {
    if (stream.pushAllowed) {
      // push app.js
        [HTTP2_HEADER_PATH]: '/app.js'
      }, (err, pushStream) => {
        if (!err) {
          sendFile(pushStream, path.join(__dirname, publicLocation, 'app.js'));

      // push style.css
        [HTTP2_HEADER_PATH]: '/style.css'
      }, (err, pushStream) => {
        if (!err) {
          sendFile(pushStream, path.join(__dirname, publicLocation, 'style.css'));

    // send index.html
    let indexFileLocation = path.join(__dirname, publicLocation, 'index.html');
    sendFile(stream, indexFileLocation);

  } else { // handle other requests
      'content-type': 'text/plain; charset=utf-8',
      ':status': 200
    stream.end('hello world');

server.listen(serverPort, () => {
  console.log('HTTP2 server listen to port ' + serverPort);

Now we can start the server and open the website in a browser with the address https://localhost:3000/index.html. If we open the browser inspection tool, we can see on the network panel that the initiator of app.js and style.css requests are called "Push". In other words, those files have already been cached by the browser, and the browser isn't required to make additional HTTP requests to the server.


Popular posts from this blog

Rangkaian Sensor Infrared dengan Photo Dioda

Keunggulan photodioda dibandingkan LDR adalah photodioda lebih tidak rentan terhadap noise karena hanya menerima sinar infrared, sedangkan LDR menerima seluruh cahaya yang ada termasuk infrared. Rangkaian yang akan kita gunakan adalah seperti gambar di bawah ini. Pada saat intensitas Infrared yang diterima Photodiode besar maka tahanan Photodiode menjadi kecil, sedangkan jika intensitas Infrared yang diterima Photodiode kecil maka tahanan yang dimiliki photodiode besar. Jika  tahanan photodiode kecil  maka tegangan  V- akan kecil . Misal tahanan photodiode mengecil menjadi 10kOhm. Maka dengan teorema pembagi tegangan: V- = Rrx/(Rrx + R2) x Vcc V- = 10 / (10+10) x Vcc V- = (1/2) x 5 Volt V- = 2.5 Volt Sedangkan jika  tahanan photodiode besar  maka tegangan  V- akan besar  (mendekati nilai Vcc). Misal tahanan photodiode menjadi 150kOhm. Maka dengan teorema pembagi tegangan: V- = Rrx/(Rrx + R2) x Vcc V- = 150 / (150+10) x Vcc V- = (150/160) x 5

Setting Up Next.js Project With ESLint, Typescript, and AirBnB Configuration

If we initiate a Next.js project using the  create-next-app tool, our project will be included with ESLint configuration that we can apply using yarn run lint . By default, the tool installs eslint-config-next and extends next/core-web-vitals in the ESLint configuration. The Next.js configuration has been integrated with linting rules for React and several other libraries and tools. yarn create next-app --typescript For additional configuration such as AirBnB, it is also possible. First, we need to install the peer dependencies of eslint-config-airbnb . We also add support for Typescript using eslint-config-airbnb-typescript . yarn add --dev eslint-config-airbnb eslint-plugin-import eslint-plugin-jsx-a11y eslint-plugin-react eslint-plugin-react-hooks yarn add --dev eslint-config-airbnb-typescript @typescript-eslint/eslint-plugin @typescript-eslint/parser After that, we can update the .eslintrc.json file for the new configuration. { "extends": [ "airb

Configuring Swap Memory on Ubuntu Using Ansible

If we maintain a Linux machine with a low memory capacity while we are required to run an application with high memory consumption, enabling swap memory is an option. Ansible can be utilized as a helper tool to automate the creation of swap memory. A swap file can be allocated in the available storage of the machine. The swap file then can be assigned as a swap memory. Firstly, we should prepare the inventory file. The following snippet is an example, you must provide your own configuration. [server] [server:vars] ansible_user=root ansible_ssh_private_key_file=~/.ssh/id_rsa Secondly, we need to prepare the task file that contains not only the tasks but also some variables and connection information. For instance, we set /swapfile  as the name of our swap file. We also set the swap memory size to 2GB and the swappiness level to 60. - hosts: server become: true vars: swap_vars: size: 2G swappiness: 60 For simplicity, we only check the exi

Raspberry Pi Bluetooth Connection

Raspberry Pi 3 provides a built-in Bluetooth module. The latest Raspbian has been bundled with tools for enabling Bluetooth connection. The Bluetooth icon will be shown up on the top right corner of the desktop. It's a tool to discover available Bluetooth devices and connect Pi with Bluetooth devices. It is easy to connect any Bluetooth-enabled electronic device with Pi. But, sometimes Pi will fail to connect, especially for Bluetooth device that has no standardized services. From a terminal, we can use the  bluetoothctl tool to scan and connect with a Bluetooth device. You should make sure that the BlueZ protocol stack has been installed by running $ apt-get install bluez Run bluetoothctl to enter the tool command window Turn the power on by running power on (Optional) You can set AutoEnable=true in /etc/bluetooth/main.conf if you want to make the Bluetooth auto power-on after reboot. Run devices to see which devices have been paired Run scan on if your desired d

Installing Multiple Instances of Linux Distributions in WSL

By support of WSL (Windows Subsystem for Linux), you can install any Linux distros in a Windows machine. Recommended method from WSL documentation is by downloading the distribution from Microsoft Store or find .appx installation file available in Microsoft website. For running multiple instances of same Linux distribution, you can duplicate the data using export-import procedure, as I have mentioned in another post . Another method that might be more beneficial is by utilizing Docker. Currently, Docker has already had variety of images of Linux distributions in its registry. You can also store your own costumized distribution in Docker registry that can be distributed to any machines instantly. After you had WSL 2 and an installed Linux distribution from Microsoft Store, you are ready to have more Linux instances in your Windows. 1. List all installed distributions in your Windows. wsl --list -v 2. Run the distribution you desired from terminal, for example, you have insta

Generate API Documentation Using Swagger Module in NestJS

Swagger provides us a standard to generate API documentation based on the Open API specification. If we use NestJS for building our API providers, we can utilize a tool provided by NestJS in the  @nestjs/swagger  module to generate the documentation automatically in the built time. This module also requires the swagger-ui-express module if we use Express as the NestJS base HTTP handler. Set Swagger configuration First, we need to define Swagger options and instantiate the documentation provider on the main.ts file. import { DocumentBuilder, SwaggerModule } from '@nestjs/swagger'; // sample application instance const app = await NestFactory.create(AppModule); // setup Swagger options const options = new DocumentBuilder() .setTitle('Coffee') .setVersion('1.0') .setDescription('Learn NestJS with coffee') .build(); // build the document const document = SwaggerModule.createDocument(app, options); // provide an endpoint