res.app Property in Express.js

The res.app property holds a reference to the instance of an Express Application that is being used by the middleware.

Syntax

res.app

Example 1

Create a file with the name "resApp.js" and copy the following code snippet. After creating the file, use the command "node resApp.js" to run this code as shown in the example below −

// res.app code Demo Example

// Importing the express module
var express = require('express');

// Initializing the express and port number
var app = express();
var PORT = 3000;

// Creating an endpoint
app.get('/', function (req, res) {
   console.log(res.app.get('views'));
   res.end();
});
app.listen(PORT, function(err){
   if (err) console.log(err);
   console.log("Server listening on PORT", PORT);
});

Hit the following URL endpoint for a GET request − http://localhost:3000/

Output

C:\home\node>> node resApp.js
Server listening on PORT 3000
/home/express/test/views

Example 2

Let's take a look at one more example.

// req.range() code Demo Example

// Importing the express module
var express = require('express');

// Initializing the express and port number
var app = express();
var PORT = 3000;

// Creating an endpoint
app.get('/', function (req, res) {
   console.log(req.range());
   res.end();
});
app.listen(PORT, function(err){
   if (err) console.log(err);
   console.log("Server listening on PORT", PORT);
});

Hit the following URL endpoint for a GET request − http://localhost:3000/

Output

C:\home\node>> node resApp.js
settings:
{ 'x-powered-by': true,
etag: 'weak',
'etag fn': [Function: generateETag],
env: 'development',
'query parser': 'extended',
'query parser fn': [Function: parseExtendedQueryString],
'subdomain offset': 2,
'trust proxy': false,
'trust proxy fn': [Function: trustNone],
view: [Function: View],
views: '/home/express/test/views',
'jsonp callback name': 'callback' },
locals:
[Object: null prototype] {
settings:
{ 'x-powered-by': true,
etag: 'weak',
'etag fn': [Function: generateETag],
env: 'development',
'query parser': 'extended',
'query parser fn': [Function: parseExtendedQueryString],
'subdomain offset': 2,
'trust proxy': false,
'trust proxy fn': [Function: trustNone],
view: [Function: View],
views: '/home/mayankaggarwal/mysql-test/views',
'jsonp callback name': 'callback' } },
mountpath: '/',
_router:
{ [Function: router]
params: {},
_params: [],
caseSensitive: false,
mergeParams: undefined,
strict: false,
stack: [ [Layer], [Layer], [Layer] ] } }