Node.js | Response Object

Hello folks! welcome back to a new edition of our tutorial on Node.js. In this section of our tutorial on Node.js, we will be studying about Node.js Response Object.

The Node.js res object represents the HTTP response that an Express application sends when it gets an HTTP request.

Response Object Properties

The following table below is the list of a few properties associated with response object -

Sr.No.	Properties & Description
1	res.app This property holds a reference to the instance of the express application that is using the middleware.
2	res.headersSent Boolean property that indicates if the app sent HTTP headers for the response.
3	res.locals An object that contains response local variables scoped to the request

READ: Node.js | Request Object

Response Object Methods

res.append(field [, value])

res.append(field [, value])

This method appends the specified value to the HTTP response header field.

Example

Following below is a simple example -

res.append('Link', ['<http://localhost/>', '<http://localhost:3000/>']);
res.append('Set-Cookie', 'foo=bar; Path=/; HttpOnly');
res.append('Warning', '199 Miscellaneous warning');

res.attachment([filename])

res.attachment([filename])

This method is used for sending a file as an attachment in the HTTP response.

Example

Following below is a simple example -

res.attachment('path/to/logo.png');

res.cookie(name, value [, options])

res.cookie(name, value [, options])

This method is used to set cookie name to value. The value parameter may be a string or object converted to JSON.

Example

Following below is a simple example -

res.cookie('name', 'tobi', { domain: '.example.com', path: '/admin', secure: true });

res.cookie('cart', { items: [1,2,3] });
res.cookie('cart', { items: [1,2,3] }, { maxAge: 900000 });

res.clearCookie(name [, options])

res.clearCookie(name [, options])

This method clears the cookie specified by name.

Example

Following below is a simple example -

res.cookie('name', 'tobi', { path: '/admin' });
res.clearCookie('name', { path: '/admin' });

res.download(path [, filename] [, fn])

res.download(path [, filename] [, fn])

This method is used for transferring the file at path as "attachment". Typically browsers will prompt the user for download.

Example

Following below is a simple example -

res.download('/report-12345.pdf');

res.download('/report-12345.pdf', 'report.pdf');

res.download('/report-12345.pdf', 'report.pdf', function(err){

});

res.end([data] [, encoding])

res.end([data] [, encoding])

This method ends the response process.

Example

Following below is a simple example -

res.end();

res.status(404).end();

READ: Node.js | File System

res.format(object)

res.format(object)

This method performs content-negotiation on the Accept HTTP header on the request object, when present.

Example

Following below is a simple example -

res.format ({
   'text/plain': function() {
      res.send('hey');
   },

   'text/html': function() {
      res.send('hey'); 
   },

   'application/json': function() {
      res.send({ message: 'hey' });
   },

   'default': function() {
      // log the request and respond with 406
      res.status(406).send('Not Acceptable');
   }
});

res.get(field)

res.get(field)

The res.get(field) method returns the HTTP response header specified by field.

Example

Following below is a simple example -

res.get('Content-Type');

res.json([body])

res.json([body])

This method sends a JSON response -

Example

Following below is a simple example -

res.json(null)
res.json({ user: 'tobi' })
res.status(500).json({ error: 'message' })

res.jsonp([body])

res.jsonp([body])

This method sends a JSON response with JSONP support.

Example

Following below is a simple example -

res.jsonp(null)
res.jsonp({ user: 'tobi' })
res.status(500).jsonp({ error: 'message' })

res.links(links)

res.links(links)

This method is used to join the links given as properties of the parameter to populate the response's Link HTTP header field.

Example

Following below is a simple example -

res.links ({
   next: 'http://api.example.com/users?page=2',
   last: 'http://api.example.com/users?page=5'
});

res.location(path)

res.location(path)

The res.location(path) method is used to set response Location HTTP header field based on the specified path parameter.

Example

Following below is a simple example -

res.location('/foo/bar');
res.location('foo/bar');
res.location('http://example.com');

READ: Node.js | Domain Module

res.redirect([status,] path)

res.redirect([status,] path)

res.redirect([status,] path) method redirects the url derived from the specified path, with specified HTTP status code status.

Example

Following below is a simple example -

res.redirect('/foo/bar');
res.redirect('http://example.com');
res.redirect(301, 'http://example.com');

res.render(view [, locals] [, callback])

res.render(view [, locals] [, callback])

This method renders a view and sends the rendered HTML string to the client.

Example

Following below is a simple example -

// send the rendered view to the client
res.render('index');

// pass a local variable to the view
res.render('user', { name: 'Tobi' }, function(err, html) {
   // ...
});

res.send([body])

res.send([body])

This method sends the HTTP response.

Example

Following below is a simple example -

res.send(new Buffer('whoop'));
res.send({ some: 'json' });
res.send('<p>some html</p>');

res.sendFile(path [, options] [, fn])

res.sendFile(path [, options] [, fn])

This method is used for transferring the file at the specified path. This method sets the "Content-Type" response HTTP header field based on the filename's extension.

Example

Following is a simple example -

res.sendFile(fileName, options, function (err) {
   // ...
});

res.sendStatus(statusCode)

res.sendStatus(statusCode)

This method is used to set response HTTP status code to statusCode and then sends its string representation as response body.

Example

Following below is a simple example -

res.sendStatus(200); // equivalent to res.status(200).send('OK')
res.sendStatus(403); // equivalent to res.status(403).send('Forbidden')
res.sendStatus(404); // equivalent to res.status(404).send('Not Found')
res.sendStatus(500); // equivalent to res.status(500).send('Internal Server Error')

res.set(field [, value])

res.set(field [, value])

This method is used to set the response's HTTP header field to value.

Example

Following below is a simple example -

res.set('Content-Type', 'text/plain');

res.set ({
   'Content-Type': 'text/plain',
   'Content-Length': '123',
   'ETag': '12345'
})

res.status(code)

res.status(code)

This method is used to set the HTTP status for the response.

Example

Following below is a simple example -

res.status(403).end();
res.status(400).send('Bad Request');
res.status(404).sendFile('/absolute/path/to/404.png');

res.type(type)

res.type(type)

This method sets the Content-Type HTTP header to the MIME type.

Example

Following below is a simple example -

res.type('.html');              // => 'text/html'
res.type('html');               // => 'text/html'
res.type('json');               // => 'application/json'
res.type('application/json');   // => 'application/json'
res.type('png');                // => image/png:

READ: Node.js | Console

Alright guys! This is where we are going to be rounding up for this tutorial. In our next tutorial, we will be studying about Node.js RESTful API.

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