Express.js app.engine() Function

The app.engine() function is used to register the given template engine callback as ext. By default the Express itself will require() the engine based on the file extension.

Syntax:

app.engine(ext, callback)

Parameters: The ext parameter is the extension type like ejs, hbs, etc and callback is the function passed as parameter.

Return Value: It returns on Object.

Installation of express module:



  1. You can visit the link to Install express module. You can install this package by using this command.
    npm install express
  2. After installing express module, you can check your express version in command prompt using the command.
    npm version express
  3. After that, you can just create a folder and add a file for example, index.js. To run this file you need to run the following command.
    node index.js
  4. Create a views folder and put home.html file in it with the following code:

    Example 1:
    Filename: home.html

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    <html>
    <head>
      <title>app.engine() Demo</title>
    </head>
    <body>
        <h2>EJS Engine</h2>
    </body>
    </html>

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For example, to map the EJS template engine to “.html” files:

app.engine('html', require('ejs').renderFile);

Filename: index.js

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var express = require('express');
var app = express();
var PORT = 3000;
  
app.engine('html', require('ejs').renderFile);
    
app.get('/', function (req, res) {
    res.render("home.html")
});
  
app.listen(PORT, function(err){
    if (err) console.log(err);
    console.log("Server listening on PORT", PORT);
});

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Steps to run the program:

  1. Make sure you have installed express and ejs module using the following command:
    npm install express
    npm install ejs
    
  2. Run index.js file using below command:
    node index.js

    Output:

    Server listening on PORT 3000
    
  3. Now open your browser and go to http://localhost:3000/, you can see the following output on your browser:

    EJS Engine
    

Example 2: Filename: home.html

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<html>
<head>
  <title>app.engine() Demo</title>
</head>
<body>
    <h2>Handlebars Engine</h2>
</body>
</html>

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Filename: index.js

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var express = require('express');
var app = express();
var PORT = 3000;
  
console.log(app.engine('html', require('hbs').renderFile));
    
app.get('/', function (req, res) {
    res.render("home.html")
});
  
app.listen(PORT, function(err){
    if (err) console.log(err);
    console.log("Server listening on PORT", PORT);
});

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Steps to run the program:

  1. Make sure you have installed express and hbs module using the following command:
    npm install express
    npm install hbs
    
  2. Run index.js file using below command:
    node index.js

    Output:

    Server listening on PORT 3000
    
  3. Now open your browser and go to http://localhost:3000/, you can see the following output on your browser:

    Handlebars Engine
    

Reference: https://expressjs.com/en/4x/api.html#app.engine




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