Server-Side Rendering (SSR) with Express.js

Server-Side Rendering (SSR) is a technique that generates HTML on the server rather than on the client. With SSR, Express.js can serve dynamic content, enhancing both SEO and load performance by delivering content that search engines and users can immediately view.

Introduction to Server-Side Rendering (SSR)

In traditional client-side rendering (CSR), JavaScript code runs in the browser to render pages. With SSR, however, HTML is generated on the server and sent to the client as a fully-rendered page. This approach has advantages in terms of SEO and initial load speed, particularly for content-heavy websites.

Example:

  • Client-Side Rendering: The client downloads JavaScript and runs it to build the page.
  • Server-Side Rendering: The server renders the page into HTML and sends it to the client.

Benefits of SSR in Web Applications

The main benefits of SSR are:

  • Improved SEO: SSR ensures that search engine bots can access page content immediately.
  • Faster Initial Load: Users see rendered content faster as the server sends fully-rendered HTML.
  • Better User Experience: SSR can reduce time-to-interactive, improving user experience.

Setting Up Express.js for SSR

To start implementing SSR, you need a basic Express.js server setup that will handle rendering HTML.

1. Initialize an Express Project

				
					mkdir express-ssr
cd express-ssr
npm init -y
npm install express

2. Basic Server Setup (server.js)

				
					const express = require('express');
const app = express();

app.use(express.static('public')); // Serves static files like CSS and JavaScript

app.get('/', (req, res) => {
  res.send('<h1>Hello from Server-Side Rendering with Express!</h1>');
});

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => console.log(`Server is running on port ${PORT}`));

Templating Engines for SSR

To render dynamic HTML, we’ll use templating engines such as EJS, Pug, or Handlebars. Express provides built-in support for these engines, making SSR straightforward.

1. Install EJS as a Templating Engine

				
					npm install ejs

2. Configure EJS in Express (server.js)

				
					const express = require('express');
const app = express();

app.set('view engine', 'ejs');
app.set('views', './views'); // Folder where EJS templates are stored

app.use(express.static('public'));

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => console.log(`Server is running on port ${PORT}`));

Implementing SSR with EJS in Express.js

With EJS, you can dynamically inject data into HTML templates. Let’s create a simple web page that renders a dynamic message.

1. Creating an EJS Template

In the views folder, create a file called home.ejs:

				
					<!DOCTYPE html>
<html>
<head>
    <title>SSR with EJS</title>
</head>
<body>
    <h1>Welcome, <%= name %>!</h1>
    <p>This page is rendered on the server with EJS.</p> <script data-no-optimize="1">!function(t,e){"object"==typeof exports&&"undefined"!=typeof module?module.exports=e():"function"==typeof define&&define.amd?define(e):(t="undefined"!=typeof globalThis?globalThis:t||self).LazyLoad=e()}(this,function(){"use strict";function e(){return(e=Object.assign||function(t){for(var e=1;e<arguments.length;e++){var n,a=arguments[e];for(n in a)Object.prototype.hasOwnProperty.call(a,n)&&(t[n]=a[n])}return t}).apply(this,arguments)}function i(t){return e({},it,t)}function o(t,e){var n,a="LazyLoad::Initialized",i=new t(e);try{n=new CustomEvent(a,{detail:{instance:i}})}catch(t){(n=document.createEvent("CustomEvent")).initCustomEvent(a,!1,!1,{instance:i})}window.dispatchEvent(n)}function l(t,e){return t.getAttribute(gt+e)}function c(t){return l(t,bt)}function s(t,e){return function(t,e,n){e=gt+e;null!==n?t.setAttribute(e,n):t.removeAttribute(e)}(t,bt,e)}function r(t){return s(t,null),0}function u(t){return null===c(t)}function d(t){return c(t)===vt}function f(t,e,n,a){t&&(void 0===a?void 0===n?t(e):t(e,n):t(e,n,a))}function _(t,e){nt?t.classList.add(e):t.className+=(t.className?" 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</html>

2. Rendering the Template from Express

Update the server.js file:

				
					const express = require('express');
const app = express();

app.set('view engine', 'ejs');
app.set('views', './views');

app.get('/', (req, res) => {
  res.render('home', { name: 'User' });
});

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => console.log(`Server is running on port ${PORT}`));

Output:

When you navigate to http://localhost:3000, the server sends back the HTML

				
					<!DOCTYPE html>
<html>
<head>
    <title>SSR with EJS</title>
</head>
<body>
    <h1>Welcome, User!</h1>
    <p>This page is rendered on the server with EJS.</p> <script data-no-optimize="1">!function(t,e){"object"==typeof exports&&"undefined"!=typeof module?module.exports=e():"function"==typeof define&&define.amd?define(e):(t="undefined"!=typeof globalThis?globalThis:t||self).LazyLoad=e()}(this,function(){"use strict";function e(){return(e=Object.assign||function(t){for(var e=1;e<arguments.length;e++){var n,a=arguments[e];for(n in a)Object.prototype.hasOwnProperty.call(a,n)&&(t[n]=a[n])}return t}).apply(this,arguments)}function i(t){return e({},it,t)}function o(t,e){var n,a="LazyLoad::Initialized",i=new t(e);try{n=new CustomEvent(a,{detail:{instance:i}})}catch(t){(n=document.createEvent("CustomEvent")).initCustomEvent(a,!1,!1,{instance:i})}window.dispatchEvent(n)}function l(t,e){return t.getAttribute(gt+e)}function c(t){return l(t,bt)}function s(t,e){return function(t,e,n){e=gt+e;null!==n?t.setAttribute(e,n):t.removeAttribute(e)}(t,bt,e)}function r(t){return s(t,null),0}function u(t){return null===c(t)}function d(t){return c(t)===vt}function f(t,e,n,a){t&&(void 0===a?void 0===n?t(e):t(e,n):t(e,n,a))}function _(t,e){nt?t.classList.add(e):t.className+=(t.className?" 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</html>

This simple example shows how you can dynamically inject data into HTML templates with EJS and serve it directly from Express.

Implementing SSR with React and Express.js

In addition to EJS, you can also use modern frontend frameworks like React to implement SSR. For this setup, we’ll need additional packages.

1. Setting Up a React Component

Create a basic React component in components/Home.js:

				
					const React = require('react');

function Home({ name }) {
  return (
    <div>
      <h1>Welcome, {name}!</h1>
      <p>This page is server-side rendered with React and Express.</p>
    </div>
  );
}

module.exports = Home;

2. Installing Additional Packages

				
					npm install react react-dom server

3. Render React Component with SSR

In server.js, add code to render this component server-side:

				
					const express = require('express');
const React = require('react');
const ReactDOMServer = require('react-dom/server');
const Home = require('./components/Home');

const app = express();

app.get('/', (req, res) => {
  const component = ReactDOMServer.renderToString(React.createElement(Home, { name: 'User' }));
  const html = `
    <!DOCTYPE html>
    <html>
    <head>
        <title>SSR with React</title>
    </head>
    <body>
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    </html>
  `;
  res.send(html);
});

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => console.log(`Server is running on port ${PORT}`));

Output: When you load the page, the server sends back fully-rendered HTML for React components.

Advanced SSR Techniques

  1. Data Fetching: Integrate data fetching to send initial data directly from the server for faster loading.
  2. Hydration: Add client-side JavaScript to make components interactive after SSR.
  3. Caching: Use caching strategies to serve frequently accessed pages faster.

Testing and Optimizing SSR Applications

  • Lighthouse Testing: Check SEO, accessibility, and performance metrics.
  • Caching and Compression: Use caching and gzip to optimize server responses.

With Server-Side Rendering (SSR) in Express.js, you can deliver fast, SEO-friendly content directly to the client. Using EJS for templating is a straightforward approach to SSR, while frameworks like React enhance interactivity and scalability. Combining SSR with data fetching, hydration, and caching provides a powerful setup for responsive, user-friendly applications. Happy Coding!❤️

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