The Ultimate Guide to EJS

EJS is a simple templating language that lets you generate HTML markup with plain JavaScript. Think of it as personalizing a party invitation for every single guest.

The Core Syntax: Your Toolkit

<%= %>

Output Data (Escaped)

Your go-to tag. Safely outputs data as text, preventing security risks by escaping HTML. Perfect for user-generated content.

<%- %>

Output Raw HTML

Outputs unescaped data. Use with caution! Only for trusted content, like rendering an EJS partial with `<%- include() %>`.

<% %>

Execute Logic

The "scriptlet" tag. Use it for conditionals (`if/else`), loops (`forEach`), and defining variables. It runs the code but outputs nothing.

<%# %>

Comments

Server-side comments. They are stripped from the final HTML output, making them perfect for developer notes inside templates.

EJS in Action: The Express Render Cycle

When a user requests a page, Express follows a simple flow to combine your data and templates into a complete HTML document, which is then sent back to the browser.

HTTP Request
Express Route
res.render('template', data)
HTML Response

Common EJS Feature Usage

This chart shows a typical breakdown of how developers use EJS features. Outputting data is the primary task, followed by control flow and reusing UI with partials.

EJS Best Practices, Ranked

Prioritizing security and keeping logic out of views are the most critical best practices for writing clean, maintainable, and secure EJS applications.

Professional Workflows

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Security First

Always default to `<%= %>` to prevent XSS attacks. Treat all user input as untrusted and let EJS's default escaping protect your application.

Performance by Default

EJS automatically caches compiled templates in production. This means blazing-fast renders after the first request with zero configuration.

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Structured Views

Organize your templates into `pages/` and `partials/` directories. A clean structure is key to managing large, scalable applications.