Using Node.js with HTML : Template Engines EJS

Node.js, since its inception by Ryan Dahl in 2009, has been a game-changer in the realm of server-side web applications and APIs. Its versatility doesn't just end at creating APIs; it extends to rendering HTML on the server, a concept known as Server Side Rendering (SSR).

Delving into Server Side Rendering (SSR)

When you interact with websites built using libraries like React.js, the server typically sends over a basic HTML file accompanied by CSS and JavaScript files. This HTML is often just a skeleton, and JavaScript takes on the role of populating the DOM, a method termed Client Side Rendering.

While this method is prevalent, it's not without its challenges:

• SEO optimization for client-side rendered apps can be tricky.
• Slower devices might face extended load times, leading to a subpar user experience.
• The need to fetch data via an API can introduce additional server requests, further increasing load times.

Enter Server Side Rendering (SSR). With SSR, the server pre-renders the required content for the webpage, enhancing SEO and reducing load times.

Integrating HTML with Node.js using Express.js

Express.js, a popular web application framework for Node.js, offers a straightforward way to send HTML content to the client. Here's a glimpse of how it works:

Basic Express.js Setup

In a rudimentary Express.js setup, you might send a JSON response for the root route. To transition from a JSON response to an HTML one, you'd switch from using res.json() to res.send(). This function can handle both plain text and HTML strings, and the browser will render the received content.

For instance:

app.get('/', (req, res) => {
    res.send('<h1>Welcome to Our Node.js Guide!</h1>');
});

Dynamic HTML Rendering

For more dynamic content, you can leverage JavaScript's string manipulation capabilities:

const currentTime = new Date().toLocaleTimeString();
const greeting = `<h1>Hello! The current time is: ${currentTime}</h1>`;

However, for more extensive HTML content, embedding everything within a string isn't practical. Instead, you'd store your HTML in a .html file and send the entire file as a response using res.sendFile().

Using Templating Engines

While sending an entire HTML file is convenient, it poses challenges when you need to render dynamic content. This is where templating engines come into play.

Templating engines allow you to write HTML with a specific syntax, which, when combined with data, produces a complete HTML page. Among the many available, EJS (Embedded JavaScript Templating) stands out for its simplicity and widespread use.

Setting Up EJS with Express.js

1. Installation: Begin by installing EJS using npm:

npm install ejs

2. Configuration: Next, configure Express.js to use EJS:

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

3. Creating Templates: Store your EJS templates in a views directory. These templates can then be rendered using the res.render() function.

For dynamic content, you can pass data to your templates:

const userData = {
    name: 'John Doe'
};
res.render('templateName', userData);

Inside the EJS template, you can access this data using the <%= variableName %> syntax.

Advanced EJS Techniques

EJS supports standard JavaScript, allowing for loops, conditional statements, and more. For instance, to conditionally display content based on the presence of a username:

<% if (username) { %>
    <h1>Welcome, <%= username %>!</h1>
<% } else { %>
    <h1>Please sign in.</h1>
<% } %>

For more advanced EJS functionalities, the official EJS documentation is a valuable resource.

Advantages of Server Side Rendering

Server Side Rendering (SSR) isn't just a buzzword; it offers tangible benefits:

1. Improved SEO: Search engines can crawl and index server-rendered content more efficiently.
2. Faster Time to First Byte (TTFB): The browser receives a fully rendered page, reducing the time users wait to see the first piece of content.
3. Enhanced Performance on Low-End Devices: Devices with limited processing power benefit from SSR as the server does most of the heavy lifting.
4. Consistent User Experience: Users get a fully rendered page even if JavaScript fails or is disabled on their browser.

Best Practices for Node.js and HTML Integration

1. Optimize Asset Delivery: Minimize and compress CSS and JavaScript files. Use tools like Webpack for bundling and tree shaking.
2. Leverage Caching: Implement caching strategies to serve frequently accessed content faster.
3. Monitor Server Health: Use tools like PM2 to keep your Node.js server running smoothly and restart it if it crashes.
4. Stay Updated: Regularly update your Node.js, Express.js, and other dependencies to benefit from performance improvements and security patches.

Frequently Asked Questions (FAQs)

1. Can I use other templating engines besides EJS with Express.js?

Answer: Absolutely! Express.js is highly flexible and supports a variety of templating engines, including Pug, Mustache, Handlebars, and more.

2. How does SSR affect the performance of my Node.js server?

Answer: While SSR can increase the server's workload, the benefits often outweigh the costs. However, it's essential to monitor server performance and scale resources as needed.

3. Is SSR suitable for all web applications?

Answer: While SSR offers many advantages, it might not be the best choice for all applications, especially those that are highly interactive and frequently updated. In such cases, a hybrid approach, combining SSR with Client Side Rendering (CSR), might be more appropriate.

4. How can I optimize my server-rendered website for mobile devices?

Answer: Use responsive design techniques to ensure your website looks and functions well on all screen sizes. Additionally, consider implementing Progressive Web App (PWA) features for an app-like experience on mobile devices.

5. Can I integrate Node.js with frontend frameworks like React or Vue?

Answer: Yes, Node.js works seamlessly with frontend frameworks. In fact, frameworks like Next.js (for React) and Nuxt.js (for Vue) are specifically designed to facilitate SSR with these libraries.

Conclusion

Node.js, combined with Express.js and templating engines like EJS, offers a robust solution for rendering HTML content server-side. This approach not only enhances user experience and SEO but also simplifies the process of creating dynamic, data-driven web pages.