EJS: Embedded JavaScript Templates for Node.js

EJS (Embedded JavaScript Templates) is a lightweight templating engine for JavaScript, primarily designed for use in Node.js environments. It enables developers to inject dynamic content into HTML templates using JavaScript syntax, creating web pages that are flexible and easily customizable. Introduced in 2010 by Tj Holowaychuk, EJS has become a prominent solution for rendering views in web applications. With its simplicity, ease of integration, and efficient handling of JavaScript within HTML, it has gained wide adoption in the Node.js ecosystem.

1. Introduction to EJS

In the early days of web development, server-side rendering relied on basic HTML templates or heavily templated engines that often demanded an unnatural separation between HTML and logic. However, as JavaScript frameworks evolved, there was a growing need for more dynamic templating systems that could combine HTML structure with JavaScript functionality in a seamless way. EJS filled this gap by offering a simple, intuitive syntax that allows developers to embed JavaScript directly within their HTML code.

The core idea behind EJS is the ability to inject data into an HTML template at runtime. By using special tags (e.g., <%= %>), developers can bind data from their server-side application to the client-side templates. This results in highly dynamic web pages that update in response to user input, server data, or other changing conditions.

2. Core Features of EJS

2.1 Simple Syntax

EJS provides a minimalistic and easy-to-understand syntax for embedding JavaScript into HTML. The most common syntax used in EJS templates are:

• <%= %>: This tag outputs the value of an expression into the HTML.
• <%- %>: This tag outputs the value of an expression, but the result is not escaped (useful for HTML content).
• <% %>: This tag is used for control flow like loops and conditionals, but it does not output any value directly.

This simple syntax makes it easy for developers to manage dynamic content in their web pages without needing to deal with complex templating engines or verbose code.

2.2 Integration with Node.js

EJS is designed to work seamlessly within Node.js applications, making it a popular choice for developers using Express, a widely used web framework for Node.js. EJS templates are rendered server-side, meaning that the final HTML is generated on the server and sent to the client. This process helps optimize performance and SEO, as it allows search engines to index fully rendered content rather than relying on JavaScript execution on the client side.

2.3 Partial Views and Layouts

EJS supports the concept of partial views, allowing developers to reuse common components such as headers, footers, and sidebars across different pages of the application. This reduces redundancy in the code and improves maintainability. Partial views can be rendered with the <%- include %> syntax, which includes another template within the current one.

Layout templates allow for consistent structure across web pages. By separating the layout (header, footer, navigation, etc.) from the content, developers can easily manage the overall design and make changes to the global structure without having to update every individual template.

2.4 Conditional Statements and Loops

As with most templating engines, EJS supports control flow mechanisms such as conditionals and loops. These features allow developers to dynamically generate content based on specific conditions or iterate over data arrays to create repeating elements, such as lists or tables.

For instance, the following example shows how to use a loop to iterate over an array of users and render their names:

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  <% users.forEach(function(user) { %>
    
<%= user.name %>
  <% }); %>

This flexibility in handling dynamic data makes EJS a powerful tool for building web applications that require frequent content updates.

3. Advantages of EJS

3.1 Lightweight and Simple

One of the key advantages of EJS is its simplicity. Unlike some templating engines that come with a steep learning curve, EJS provides a straightforward syntax that is easy to learn for developers already familiar with JavaScript. Its minimalistic nature means that it does not introduce unnecessary complexity, making it ideal for small to medium-sized applications.

3.2 Fast Performance

EJS is known for its speed. Since the templates are compiled to JavaScript code, they can be executed quickly at runtime. The template rendering process is efficient, and as a result, EJS is suitable for high-performance web applications that require rapid server-side rendering.

3.3 Open Source and Community Support

EJS is an open-source project, meaning that it is freely available for anyone to use, modify, and contribute to. The open-source nature of the project has fostered a strong community of developers who contribute to the growth and improvement of the engine. EJS is actively maintained, and its GitHub repository has a healthy number of contributors, ensuring that bugs are fixed and new features are regularly added.

3.4 Versatility

EJS can be used in a variety of environments beyond Node.js. It is compatible with any JavaScript-based backend, and developers can use it to build static sites, dynamic web applications, or even desktop applications using frameworks like Electron. This versatility makes EJS a valuable tool for a wide range of projects.

4. How to Use EJS in a Node.js Application

Using EJS in a Node.js application is simple. Below is a step-by-step guide on how to integrate EJS with a basic Node.js and Express application:

4.1 Setting Up a Node.js Project

First, create a new directory for your project and navigate to it in the terminal. Then, initialize a new Node.js project by running:

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npm init -y

This will generate a package.json file. Next, install Express and EJS:

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npm install express ejs

4.2 Creating an Express Application

In your project directory, create an app.js file to set up the Express application:

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

// Set EJS as the templating engine
app.set('view engine', 'ejs');

// Serve static files from the "public" directory
app.use(express.static('public'));

// Define a route
app.get('/', (req, res) => {
  res.render('index', { title: 'EJS Example', message: 'Hello, world!' });
});

// Start the server
app.listen(3000, () => {
  console.log('Server is running on http://localhost:3000');
});

4.3 Creating the EJS Template

In the same directory as app.js, create a views folder and inside it create an index.ejs file:

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<%= message %>

In this template, the <%= %> tags are used to inject the values of the title and message variables into the HTML.

4.4 Running the Application

Finally, run your application with the following command:

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node app.js

You can now visit http://localhost:3000 in your browser, and the page will render the dynamic content from the EJS template.

5. Challenges and Considerations

While EJS is a powerful templating engine, there are a few challenges and limitations to be aware of:

• No Built-in Caching: Unlike some other templating engines, EJS does not have built-in caching for templates. Developers need to handle template caching manually, which could be a concern for large-scale applications.

• Limited Features: Compared to more feature-rich engines like Pug or Handlebars, EJS has a relatively basic set of features. While this makes it lightweight, it also means that it lacks some advanced functionality that developers might find in other engines.

• No HTML Minification: EJS does not offer automatic HTML minification, which could be a drawback in performance-critical applications where reducing page load time is important.

6. Conclusion

EJS has proven to be an excellent choice for server-side rendering in Node.js applications, offering a clean and simple solution for embedding JavaScript into HTML templates. Its minimalistic syntax, speed, and ease of integration with Node.js make it an appealing option for web developers, particularly those working with the Express framework. Although it lacks some of the advanced features found in other templating engines, its straightforward approach and active community make EJS a reliable tool for building dynamic and efficient web applications.

As web development continues to evolve, EJS will likely remain a solid choice for developers looking for a lightweight and effective way to render views and manage dynamic content on the server side. With its open-source nature and active contributions from the community, it’s clear that EJS has a bright future in the Node.js ecosystem.