Programming for beginners: Express: app.engine(ext, callback): Register template engine

app.engine(ext, callback)

Following code implements custom template engine. If any file ends with extension .ctl, it is handled by this logic.

app.engine('ctl', (filePath, options, callback) => { 

  fs.readFile(filePath, function (err, content) {
    if (err) return callback(err)
  
    var rendered = content.toString().replace('-title-', '<h1> Title: ' + options.title + '</h1>')
    .replace('-message-', '<h1> Message: ' + options.message + '</h1>')
 
 data = "<html><head><title>Demo</title><body>"+rendered+"</body></html>"
 
    return callback(null, data)
  })
  
})

Let’s create views folder and create demoFile.ctl.

demoFile.ctl

-title-
-message-

index.js

const fs = require('fs')
var express = require('express')

var app = express()

app.set('version', '1.2.31')
app.set('maintenanceSupported', true)

app.get('/', (req, res) => {
 res.render('demoFile', { title: 'Hello', message: 'How are you?' })
})

app.set('views', './views') // specify the views directory
app.set('view engine', 'ctl') // register the template engine, ctl : Custom template

const port = 8080;

app.engine('ctl', (filePath, options, callback) => { 

  fs.readFile(filePath, function (err, content) {
    if (err) return callback(err)
  
    var rendered = content.toString().replace('-title-', '<h1> Title: ' + options.title + '</h1>')
    .replace('-message-', '<h1> Message: ' + options.message + '</h1>')
 
 data = "<html><head><title>Demo</title><body>"+rendered+"</body></html>"
 
    return callback(null, data)
  })
  
})

app.listen(3000, () => {console.log("Application started in port 3000")});

Run index.js.

Open the url ‘http://localhost:3000/’ in browser, you can see below content.

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Programming for beginners

Tuesday 26 February 2019

Express: app.engine(ext, callback): Register template engine

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