Express app.engine() Method

Posted in Express Tutorial

Updated on Feb 17, 2024

By Mari Selvan

👁️ 28 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

Express.js, a widely-used web application framework for Node.js, allows developers to customize various aspects of their applications. One such feature is the app.engine() method, which enables the integration of different view engines.

In this guide, we'll explore the syntax, usage, and practical examples of the app.engine() method, providing you with the tools to tailor your application's view rendering process.

💡 Syntax

The syntax for the app.engine() method is as follows:

syntax.js

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app.engine(viewEngineName, renderFunction)

viewEngineName: A string representing the name of the view engine to register.
renderFunction: The function responsible for rendering views using the specified view engine.

❓ How app.engine() Works

The app.engine() method allows you to register custom view engines with Express.js. View engines are responsible for rendering dynamic content and templates into HTML. By default, Express uses the 'pug' view engine, but with app.engine(), you can integrate others like 'ejs', 'handlebars', or even create your own.

example.js

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

// Registering the 'ejs' view engine
app.engine('ejs', require('ejs').__express);
app.set('view engine', 'ejs');

// Your route handlers go here

const PORT = 3000;
app.listen(PORT, () => {
  console.log(`Server is running on port ${PORT}`);
});

In this example, we register the 'ejs' view engine using app.engine() and set it as the default view engine using app.set('view engine', 'ejs').

📚 Use Cases

Integration of Handlebars View Engine:

Use app.engine() to integrate the Handlebars view engine, providing a powerful and flexible templating solution.

example.js

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const express = require('express');
const exphbs = require('express-handlebars');
const app = express();

// Registering Handlebars as the view engine
app.engine('handlebars', exphbs());
app.set('view engine', 'handlebars');

// Your route handlers go here

const PORT = 3000;
app.listen(PORT, () => {
  console.log(`Server is running on port ${PORT}`);
});

Custom View Engine:

Leverage app.engine() to register a custom view engine tailored to your specific rendering requirements.

example.js

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

// Custom view engine function
const customEngine = (filePath, options, callback) => {
  // Implement your custom rendering logic here
  const renderedContent = /* Custom rendering logic */;
  return callback(null, renderedContent);
};

// Registering the custom view engine
app.engine('custom', customEngine);
app.set('view engine', 'custom');

// Your route handlers go here

const PORT = 3000;
app.listen(PORT, () => {
  console.log(`Server is running on port ${PORT}`);
});

🏆 Best Practices

Choose the Right Engine for the Task:

Select a view engine that aligns with your application's requirements and your familiarity with its syntax and features.
example.js
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```
// Choosing 'handlebars' for its simplicity and widespread usage
app.engine('handlebars', exphbs());
app.set('view engine', 'handlebars');
```
Keep View Logic Separate:

Separate view logic from route handlers by placing views in a dedicated 'views' directory. This enhances code organization and maintainability.
example.js
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```
project/
|-- views/
|   |-- index.ejs
|   |-- layout.ejs
|-- app.js
```

🎉 Conclusion

The app.engine() method in Express.js provides a powerful way to customize view engines, allowing you to tailor the rendering process to suit your application's needs. Whether integrating popular engines like Handlebars or creating your own, understanding how to use app.engine() enhances your ability to craft dynamic and engaging web applications.

Now equipped with knowledge about the app.engine() method, venture forth and enhance your Express.js projects with personalized view engine configurations!