Cookie Management in Express

What is a cookie?

Cookies are small pieces of data sent from a website and are stored in user's web browser while user is browsing that website. Every time the user loads that website back, the browser sends that stored data back to website or server, to distinguish user's previous activity.

What is Express?

Express is a minimal and flexible Node.js web application framework that provides a robust set of features for web and mobile applications.
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How Does Express Look Like?

var express = require('express');

var app = express();

app.get('/', function (req, res) {
  res.send('Hello World!');
});

var server = app.listen(3000, function () {

  var host = server.address().address;
  var port = server.address().port;

  console.log('Example app listening at http://%s:%s', host, port);

});

Hello world express

Installation

So far we have seen, what is cookie and how a basic express app would look like.
But now I will show you how to acquire cookie abilities in express. The very first thing you would be doing is to install cookie-parser middleware through npm into node_modules folder which can be found in your app folder. And to install it :

1. Open your terminal,
2. Browse to your app folder,

$ npm install cookie-parser

cookie-parser

Using Cookie-Parser

Import** cookie-parser** into your app

var express = require('express');
var cookieParser = require('cookie-parser');

var app = express();
app.use(cookieParser());

Syntax

Cookie-parser parses Cookie header and populate req.cookies with an object keyed by the cookie names. To set a new cookie lets define a new route in your express app like :

app.get('/cookie',function(req, res){
     res.cookie(cookie_name , 'cookie_value').send('Cookie is set');
});

To check whether cookie has been set or not, goto to browser's console and write document.cookie.

Browser sends back that cookie to the server, every time when it requests that website. And to get a cookie which a browser might be sending to server by attaching it to request header, we can write following code :

app.get('/', function(req, res) {
  console.log("Cookies :  ", req.cookies);
});

How to Set Cookie Expiration Time?

Cookie expire time can be set easily by :

res.cookie(name , 'value', {expire : new Date() + 9999});

Addition options for cookies can be set be passing an object as argument which carries additional settings for cookies. So, to set expire time to cookies, an object with expire property can be sent which holds the expire time in milliseconds.

An alternate approach to set cookie expiration age is to use optional magAge property.

res.cookie(name, 'value', {maxAge : 9999});

How to Delete Existing Cookie?

Existing cookies can be deleted very easily using clearCookie method, which accepts the name of the cookie which you want to delete.

app.get('/clearcookie', function(req,res){
     clearCookie('cookie_name');
     res.send('Cookie deleted');
});

Now, once again you can go and check in browser's console that the particular cookie has been deleted.