Server Side Rendering

Server-Side Rendering (SSR) is a technique used in web development to render web pages on the server instead of the client. This chapter will cover SSR from basic concepts to advanced techniques, providing a detailed understanding and practical examples. By the end of this chapter, you will have a comprehensive knowledge of SSR in React, its benefits, how it works, and how to implement it in your projects.

What is Server-Side Rendering (SSR)?

Server-Side Rendering (SSR) refers to the process of rendering web pages on the server rather than on the client. In SSR, the server generates the HTML content of the page, which is then sent to the client’s browser. This contrasts with Client-Side Rendering (CSR), where the rendering happens on the client after the initial HTML is loaded.

Why Use Server-Side Rendering?

There are several reasons to use SSR in web applications:

Improved Performance: SSR can deliver content faster to the user, especially for users with slow internet connections, as the HTML is already rendered on the server.
SEO Benefits: Search engines can easily index pre-rendered HTML content, improving the SEO of your web pages.
Initial Page Load: The initial load time is often faster with SSR because the browser receives fully rendered HTML, allowing users to see content sooner.

How Server-Side Rendering Works

In SSR, the server processes the React components and converts them into HTML before sending the response to the client. The client then receives the fully rendered HTML page and displays it. After the initial load, React takes over and manages subsequent updates to the DOM.

Here’s a simplified workflow of SSR:

Request: The client requests a web page.
Server Processing: The server processes the request, runs the React application, and renders the components into HTML.
Response: The server sends the rendered HTML to the client.
Hydration: The client receives the HTML, React attaches event handlers, and takes over subsequent updates.

Setting Up SSR with React

To set up SSR with React, you typically use Node.js and a server framework like Express. Here’s a step-by-step guide to setting up a basic SSR application:

Step 1: Create a React Application

				
					npx create-react-app ssr-example
cd ssr-example

Step 2: Set Up a Server

				
					npm install express react-dom/server

Create a server.js file in the root of your project:

				
					// server.js
const express = require('express');
const React = require('react');
const ReactDOMServer = require('react-dom/server');
const App = require('./src/App').default;

const app = express();

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

app.get('*', (req, res) => {
    const app = ReactDOMServer.renderToString(React.createElement(App));

    const html = `
        <!DOCTYPE html>
        <html lang="en">
        <head>
            <meta charset="UTF-8">
            <meta name="viewport" content="width=device-width, initial-scale=1.0">
            <title>SSR Example</title>
            <link rel="stylesheet" href="/static/css/main.css">
        </head>
        <body>
            <div id="root">${app}</div> <script type="litespeed/javascript" data-src="/static/js/bundle.js"></script> <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>
    `;
    res.send(html);
});

app.listen(3000, () => {
    console.log('Server is running on port 3000');
});

Step 3: Build the React Application

				
					npm run build

Step 4: Run the Server

				
					node server.js

Now, when you navigate to http://localhost:3000, you should see your React application rendered on the server.

Practical Examples

Example 1: Basic SSR with React

In this example, we’ll create a simple React application that renders a welcome message on the server and sends the pre-rendered HTML to the client.

Components

App.js: A simple React component that displays a welcome message.
server.js: An Express server that handles SSR.

Code

Step 1: Create the React Application

First, create a basic React application:

				
					npx create-react-app ssr-basic-example
cd ssr-basic-example

Step 2: Set Up the React Component

Create an App.js file inside the src directory:

				
					// src/App.js
import React from 'react';

function App() {
    return (
        <div>
            <h1>Welcome to Server-Side Rendering with React</h1>
            <p>This is a basic example of SSR with React.</p>
        </div>
    );
}

export default App;

Step 3: Set Up the Express Server

Install Express and React DOM Server:

				
					npm install express react-dom/server

Create a server.js file in the root of your project:

				
					// server.js
const express = require('express');
const React = require('react');
const ReactDOMServer = require('react-dom/server');
const App = require('./src/App').default;

const app = express();

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

app.get('*', (req, res) => {
    const app = ReactDOMServer.renderToString(<App />);

    const html = `
        <!DOCTYPE html>
        <html lang="en">
        <head>
            <meta charset="UTF-8">
            <meta name="viewport" content="width=device-width, initial-scale=1.0">
            <title>SSR Example</title>
            <link rel="stylesheet" href="/static/css/main.css">
        </head>
        <body>
            <div id="root">${app}</div> <script type="litespeed/javascript" data-src="/static/js/bundle.js"></script> <script data-no-optimize="1">!function(t,e){"object"==typeof exports&&"undefined"!=typeof module?module.exports=e():"function"==typeof define&&define.amd?define(e):(t="undefined"!=typeof globalThis?globalThis:t||self).LazyLoad=e()}(this,function(){"use strict";function e(){return(e=Object.assign||function(t){for(var e=1;e<arguments.length;e++){var n,a=arguments[e];for(n in a)Object.prototype.hasOwnProperty.call(a,n)&&(t[n]=a[n])}return t}).apply(this,arguments)}function i(t){return e({},it,t)}function o(t,e){var n,a="LazyLoad::Initialized",i=new t(e);try{n=new CustomEvent(a,{detail:{instance:i}})}catch(t){(n=document.createEvent("CustomEvent")).initCustomEvent(a,!1,!1,{instance:i})}window.dispatchEvent(n)}function l(t,e){return t.getAttribute(gt+e)}function c(t){return l(t,bt)}function s(t,e){return function(t,e,n){e=gt+e;null!==n?t.setAttribute(e,n):t.removeAttribute(e)}(t,bt,e)}function r(t){return s(t,null),0}function u(t){return null===c(t)}function d(t){return c(t)===vt}function f(t,e,n,a){t&&(void 0===a?void 0===n?t(e):t(e,n):t(e,n,a))}function _(t,e){nt?t.classList.add(e):t.className+=(t.className?" 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d=document.createElement("script");d.addEventListener("load",e),d.addEventListener("error",e),t.getAttributeNames().forEach(e=>{"type"!=e&&d.setAttribute("data-src"==e?"src":e,t.getAttribute(e))});let a=!(d.type="text/javascript");!d.src&&t.textContent&&(d.src=litespeed_inline2src(t.textContent),a=!0),t.after(d),t.remove(),a&&e()}function litespeed_inline2src(t){try{var d=urlCreator.createObjectURL(new Blob([t.replace(/^(?:<!--)?(.*?)(?:-->)?$/gm,"$1")],{type:"text/javascript"}))}catch(e){d="data:text/javascript;base64,"+btoa(t.replace(/^(?:<!--)?(.*?)(?:-->)?$/gm,"$1"))}return d}</script></body>
        </html>
    `;
    res.send(html);
});

app.listen(3000, () => {
    console.log('Server is running on port 3000');
});

Step 4: Build the React Application

Build the React application to generate the static assets:

				
					npm run build

Step 5: Run the Server

Start the server

				
					node server.js

Explanation

App.js: A simple React component that displays a welcome message.
server.js: Sets up an Express server that renders the App component to a string using ReactDOMServer.renderToString and serves the HTML.

Output

When you visit http://localhost:3000, the server sends the pre-rendered HTML, and you see the “Welcome to Server-Side Rendering with React” message immediately.

Example 2: SSR with Data Fetching

In this example, we’ll create a React application that fetches data from an API on the server before rendering the component and sending the pre-rendered HTML to the client.

Components

App.js: A React component that fetches and displays data from an API.
server.js: An Express server that handles SSR and data fetching.

Code

Step 1: Create the React Application

First, create a basic React application

				
					npx create-react-app ssr-data-fetching-example
cd ssr-data-fetching-example

Step 2: Set Up the React Component

Create an App.js file inside the src directory:

				
					// src/App.js
import React, { useState, useEffect } from 'react';

function App({ initialData }) {
    const [data, setData] = useState(initialData);

    useEffect(() => {
        if (!initialData) {
            fetch('https://jsonplaceholder.typicode.com/posts/1')
                .then(response => response.json())
                .then(json => setData(json));
        }
    }, [initialData]);

    if (!data) {
        return <div>Loading...</div>;
    }

    return (
        <div>
            <h1>{data.title}</h1>
            <p>{data.body}</p>
        </div>
    );
}

export default App;

Step 3: Set Up the Express Server

Install Express, React DOM Server, and node-fetch:

				
					npm install express react-dom/server node-fetch

Create a server.js file in the root of your project:

				
					// server.js
const express = require('express');
const React = require('react');
const ReactDOMServer = require('react-dom/server');
const fetch = require('node-fetch');
const App = require('./src/App').default;

const app = express();

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

app.get('*', async (req, res) => {
    const data = await fetch('https://jsonplaceholder.typicode.com/posts/1').then(response => response.json());
    const app = ReactDOMServer.renderToString(<App initialData={data} />);

    const html = `
        <!DOCTYPE html>
        <html lang="en">
        <head>
            <meta charset="UTF-8">
            <meta name="viewport" content="width=device-width, initial-scale=1.0">
            <title>SSR Example with Data Fetching</title>
            <link rel="stylesheet" href="/static/css/main.css">
        </head>
        <body>
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d=document.createElement("script");d.addEventListener("load",e),d.addEventListener("error",e),t.getAttributeNames().forEach(e=>{"type"!=e&&d.setAttribute("data-src"==e?"src":e,t.getAttribute(e))});let a=!(d.type="text/javascript");!d.src&&t.textContent&&(d.src=litespeed_inline2src(t.textContent),a=!0),t.after(d),t.remove(),a&&e()}function litespeed_inline2src(t){try{var d=urlCreator.createObjectURL(new Blob([t.replace(/^(?:<!--)?(.*?)(?:-->)?$/gm,"$1")],{type:"text/javascript"}))}catch(e){d="data:text/javascript;base64,"+btoa(t.replace(/^(?:<!--)?(.*?)(?:-->)?$/gm,"$1"))}return d}</script></body>
        </html>
    `;
    res.send(html);
});

app.listen(3000, () => {
    console.log('Server is running on port 3000');
});

Step 4: Hydrate the Client-Side App

Modify the index.js file in the src directory:

				
					// src/index.js
import React from 'react';
import ReactDOM from 'react-dom';
import App from './App';

const initialData = window.__INITIAL_DATA__;

ReactDOM.hydrate(<App initialData={initialData} />, document.getElementById('root'));

Step 5: Build the React Application

Build the React application to generate the static assets:

				
					npm run build

Step 6: Run the Server

Start the server:

				
					node server.js

Explanation

App.js: A React component that fetches data from an API. If initialData is provided, it uses that data; otherwise, it fetches the data on the client side.
server.js: Sets up an Express server that fetches data from the API, renders the App component to a string with the initial data, and serves the HTML.
index.js: Hydrates the client-side app with the initial data passed from the server.

Output

When you visit http://localhost:3000, the server fetches the data from the API, pre-renders the App component with the data, and sends the HTML to the client. The client hydrates the app with the initial data, and you see the content immediately.

Advanced Topics

Code Splitting with SSR

Code splitting allows you to load only the necessary code for a page, reducing the initial load time. Libraries like React.lazy and React.Suspense enable code splitting in React.

				
					import React, { Suspense, lazy } from 'react';

const LazyComponent = lazy(() => import('./LazyComponent'));

function App() {
    return (
        <div>
            <h1>Code Splitting with SSR</h1>
            <Suspense fallback={<div>Loading...</div>}>
                <LazyComponent />
            </Suspense>
        </div>
    );
}

export default App;

Hydration

Hydration is the process of attaching event listeners and making the static HTML interactive on the client side. React uses ReactDOM.hydrate instead of ReactDOM.render for this purpose.

				
					import React from 'react';
import ReactDOM from 'react-dom';
import App from './App';

ReactDOM.hydrate(<App />, document.getElementById('root'));

Using Next.js for SSR

Next.js is a popular framework for React that provides built-in support for SSR, static site generation (SSG), and more.

Setup

				
					npx create-next-app ssr-next-example
cd ssr-next-example

Code (pages/index.js):

				
					import React from 'react';

function HomePage({ data }) {
    return (
        <div>
            <h1>{data.title}</h1>
            <p>{data.body}</p>
        </div>
    );
}

export async function getServerSideProps() {
    const res = await fetch('https://jsonplaceholder.typicode.com/posts/1');
    const data = await res.json();

    return {
        props: {
            data,
        },
    };
}

export default HomePage;

Explanation

getServerSideProps fetches data on the server before rendering the page.
Next.js handles the SSR and hydration automatically.

Performance Considerations

Caching: Implement caching strategies to reduce server load and improve response times.
Lazy Loading: Use lazy loading for non-critical resources to speed up the initial load.
Optimize Assets: Compress and optimize images, scripts, and stylesheets.

Common Pitfalls and Best Practices

Avoid Blocking Operations: Ensure server-side code is non-blocking to handle concurrent requests efficiently.
Manage State Properly: Ensure that state is consistent between the server and client to avoid hydration issues.
Security: Protect against server-side vulnerabilities and ensure sensitive data is handled securely.

Summary

What is SSR?: Rendering web pages on the server and sending the HTML to the client.
Benefits: Improved performance, better SEO, and faster initial page load.
Setup: Use Node.js and Express to set up a basic SSR application.
Advanced Topics: Code splitting, hydration, and using Next.js for SSR.
Performance Considerations: Caching, lazy loading, and asset optimization.
Best Practices: Avoid blocking operations, manage state properly, and ensure security.

Server-Side Rendering (SSR) is a powerful technique for improving the performance and SEO of React applications. By understanding how SSR works and implementing best practices, you can create fast, efficient, and search engine-friendly web applications.Happy coding !❤️

Server Side Rendering

What is Server-Side Rendering (SSR)?

Why Use Server-Side Rendering?

How Server-Side Rendering Works

Setting Up SSR with React

Step 1: Create a React Application

Step 2: Set Up a Server

Create a server.js file in the root of your project:

Step 3: Build the React Application

Step 4: Run the Server

Practical Examples

Example 1: Basic SSR with React

Components

Code

Step 1: Create the React Application

Step 2: Set Up the React Component

Step 3: Set Up the Express Server

Step 4: Build the React Application

Step 5: Run the Server

Explanation

Output

Example 2: SSR with Data Fetching

Components

Code

Step 1: Create the React Application

Step 2: Set Up the React Component

Step 3: Set Up the Express Server

Step 4: Hydrate the Client-Side App

Step 5: Build the React Application

Step 6: Run the Server

Explanation

Output

Advanced Topics

Code Splitting with SSR

Hydration

Using Next.js for SSR

Setup

Code (pages/index.js):

Explanation

Performance Considerations

Common Pitfalls and Best Practices

Summary

Table of Contents

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