How To Use EJS Template Node.js Application

What is EJS and Why Use It

EJS is a simple templating language that generates HTML markup with plain JavaScript. The name stands for Embedded JavaScript, reflecting its core philosophy: embed JavaScript directly into your templates to create dynamic content without learning an entirely new syntax or paradigm. This approach makes EJS particularly attractive for developers transitioning from traditional server-side rendering patterns or those who prefer having the full power of JavaScript available within their templates (EJS Official Documentation).

The primary advantage of EJS lies in its simplicity and flexibility. Unlike some templating engines that impose strict separation between logic and presentation, EJS embraces the idea that template logic is often necessary for creating rich, data-driven user experiences. You can write standard JavaScript expressions, conditionals, and loops directly within your templates, making it straightforward to iterate over collections, conditionally render content, and transform data for display. This flexibility comes without sacrificing performance, as EJS compiles templates to optimized JavaScript functions that execute efficiently on the server (LogRocket).

EJS serves as an excellent choice for several use cases. It's particularly well-suited for building server-rendered web applications where you want to maintain the simplicity of traditional MVC patterns. EJS excels when you need to generate emails with dynamic content, create administrative dashboards that pull data from databases, or build prototypes that require rapid iteration on template logic. The engine also integrates seamlessly with Express.js, making it a natural fit for Node.js web applications that benefit from server-side rendering without the complexity of more elaborate frameworks (GeeksforGeeks).

For teams working on modern web applications, understanding templating engines like EJS complements your broader web development capabilities. While frameworks like React and Next.js handle client-side rendering effectively, server-side templating remains valuable for SEO-critical pages, email generation systems, and applications where initial page load performance is paramount. Understanding these fundamentals also pairs well with our Node.js development services for building robust backend APIs.

Setting Up EJS with Express

Integrating EJS with an Express application requires only a few straightforward steps. First, ensure you have Node.js installed and initialize a new project with npm init. Then install the required dependencies using npm install ejs express, which adds both the EJS templating engine and the Express framework to your project. With these packages in place, you can configure Express to use EJS as its view engine and specify the directory where your templates will reside.

The configuration process involves setting the view engine to 'ejs' and specifying the views directory where Express will look for template files. This setup enables you to render templates simply by calling res.render() with the template name, passing any necessary data as an argument that EJS will make available within the template. When combined with our backend development services, EJS provides a solid foundation for building dynamic server-rendered applications. For teams exploring different rendering approaches, EJS offers a straightforward alternative to more complex solutions like those covered in our AI automation services when considering intelligent content generation pipelines.

EJS Syntax and Tags

Understanding EJS's tag system is fundamental to writing effective templates. EJS provides several tag types, each serving a specific purpose in the template rendering process. The most commonly used tags are the output tags <%= %> and <%- %>, which insert values into the rendered output, and the scriptlet tags <% %>, which execute JavaScript without producing output. Knowing when to use each tag type enables you to construct templates that are both powerful and maintainable (EJS Official Documentation).

Output and Scriptlet Tags

The <%= %> tag outputs the result of a JavaScript expression after HTML-escaping it, making it safe for displaying user-provided content that might otherwise contain HTML special characters. This escaping prevents cross-site scripting (XSS) vulnerabilities and should be your default choice when displaying dynamic content. The <%- %> tag, in contrast, outputs unescaped content, which is useful when you intentionally want to render raw HTML or when you've already sanitized the content elsewhere in your application.

The <% %> scriptlet tag executes JavaScript code without producing any output. This tag is essential for control flow operations like conditionals and loops. You can wrap JavaScript logic inside these tags to control what gets rendered based on application state. For example, <% if (user.isAdmin) { %> followed by admin-only content and closed with <% } %> creates conditional rendering logic directly within the template. Similarly, <% items.forEach(function(item) { %> with <% }) %> creates loops that generate repeated HTML structures.

Working with Variables and Data

Passing data from your route handlers to EJS templates is straightforward: include the data as the second argument to res.render(). This data becomes available within the template as local variables, allowing direct access without any additional notation. You can pass simple values like strings and numbers, complex objects with nested properties, and arrays or other iterables that template logic can process (LogRocket).

Partials and Template Composition

Reusable template components are essential for maintaining large applications without code duplication. EJS's include directive provides this capability, allowing you to extract common elements like headers, footers, and navigation into separate files that can be included wherever needed. This approach promotes consistency across pages while centralizing the maintenance of shared components (EJS Official Documentation).

Creating and Using Partials

Partials are simply EJS templates stored in your views directory, typically in a dedicated partials or includes subdirectory for organization. A header partial might contain the HTML head section, navigation, and opening body tag, while a footer partial contains closing tags and any global scripts. These partials can include dynamic content by accepting variables when they're included, enabling flexible component design.

Including partials uses the <%- include() %> tag with the partial's filename (relative to the views directory) as an argument. You can pass local variables by including them in an object as the second argument. For example, <%- include('partials/header', { title: 'Home Page' }) %> includes a header partial while passing a title variable for the partial to use. This mechanism enables powerful component patterns where partials can adapt their behavior based on the context in which they're included.

Layout Patterns and Template Structure

While EJS doesn't provide a built-in layout system like some other templating engines, you can achieve similar results through careful organization of your partials and templates. A common pattern involves creating a base template that defines the overall page structure, then using includes for consistent header and footer content. This approach ensures that all pages share common elements like meta tags, stylesheet links, and navigation while allowing page-specific content to vary.

Best Practices for EJS Development

Developing maintainable EJS templates requires attention to several key practices that separate well-structured templates from tangled code. Template logic should be kept minimal, with complex processing handled in route handlers or dedicated helper modules before data reaches the template. This separation maintains the MVC pattern's benefits while keeping templates focused on presentation concerns.

Performance Optimization

EJS includes caching mechanisms that significantly improve performance for production applications. By enabling the cache option, EJS stores compiled template functions in memory, eliminating the need to recompile templates on each request. This is particularly valuable for applications serving many requests or with many templates, where the compilation overhead can become noticeable. Template structure also impacts performance--avoid complex logic or deep nesting that creates excessive function calls during rendering.

Security Considerations

Security in EJS templates centers on proper output escaping and careful handling of user-provided content. Always use <%= %> tags for displaying user input, which automatically escapes HTML entities to prevent XSS attacks. Only use unescaped output tags <%- %> with content you've explicitly sanitized elsewhere in your application or when rendering trusted HTML from your own code. Avoid directly rendering unvalidated user input as template names or paths, and be cautious about including partials with paths constructed from user input.

These security principles align with our broader approach to secure web development practices, ensuring your templating layer doesn't become a vulnerability vector. For organizations requiring enterprise-grade security, our SEO services include security auditing as part of comprehensive site health assessments.

Complete Example: EJS with Express

Putting it all together, this complete example demonstrates EJS integration with Express, showing how to configure the environment, define routes, pass data to templates, and render dynamic content. The server handles route definitions, the views directory contains templates organized with partials, and the rendering process combines template code with application data to produce final HTML output.

This example illustrates how EJS templates can serve as the view layer in a traditional MVC architecture, complementing your Node.js backend development work. By following these patterns, you can build maintainable applications where the presentation layer remains clean and focused while business logic lives in route handlers. For teams exploring automated content workflows, understanding how template engines work provides foundational knowledge for building systems that generate dynamic content at scale.

Conclusion

EJS provides a straightforward, powerful approach to server-side templating in Node.js applications. Its simplicity--embedding JavaScript directly in templates--makes it accessible while its feature set addresses most templating requirements. By understanding EJS's tag system, variable handling, and composition patterns, you can build maintainable templates that generate dynamic HTML efficiently.

Key takeaways:

1. Simplicity First: EJS's JavaScript-based syntax has minimal learning curve
2. Security Matters: Always escape user content with <%= %>
3. Organization: Use partials for reusable components
4. Performance: Enable caching in production
5. Choose Wisely: Use EJS for server-rendering, consider React/Next.js for SPAs

Whether you're building a simple dynamic website or need templating for emails and administrative interfaces, EJS offers a reliable foundation for generating dynamic content in Node.js applications. For projects requiring more sophisticated frontend interactivity, consider how EJS complements our full-stack development capabilities, providing server-side rendering where it matters most while allowing client-side frameworks to handle dynamic user interactions.

Sources

1. EJS Official Documentation - Official documentation for features, installation, and configuration
2. LogRocket: How to use EJS to template your Node.js application - Best practices and common mistakes to avoid
3. GeeksforGeeks: EJS Template Engine for Express - Express integration and practical examples