connect-flash

What is connect-flash?

The connect-flash npm package is used to create flash messages in web applications. Flash messages are temporary messages that are stored in the session and can be displayed to the user on the next request. This is particularly useful for displaying success, error, or informational messages after a form submission or other user actions.

What are connect-flash's main functionalities?

Setting Flash Messages

This feature allows you to set flash messages in your application. In this example, a flash message with the type 'info' and the message 'Flash Message Added' is set and the user is redirected to the home page.

app.get('/set-flash', function(req, res){
  req.flash('info', 'Flash Message Added');
  res.redirect('/');
});

Displaying Flash Messages

This feature allows you to display flash messages to the user. In this example, the flash messages of type 'info' are retrieved and passed to the view template to be displayed.

app.get('/', function(req, res){
  res.render('index', { messages: req.flash('info') });
});

Other packages similar to connect-flash

express-flash

The express-flash package is similar to connect-flash but is specifically designed to work with Express 4.x. It provides a simple way to flash messages to the session and display them to the user. It is a wrapper around connect-flash with additional middleware to make it compatible with Express 4.x.

express-session

The express-session package is a general-purpose session middleware for Express. While it does not provide flash message functionality out of the box, it can be used in conjunction with other packages like connect-flash or express-flash to store flash messages in the session.

flash

The flash package is a simple flash message middleware for Express. It is similar to connect-flash but is designed to be more lightweight and straightforward. It provides basic functionality for setting and displaying flash messages.

README

connect-flash

The flash is a special area of the session used for storing messages. Messages are written to the flash and cleared after being displayed to the user. The flash is typically used in combination with redirects, ensuring that the message is available to the next page that is to be rendered.

This middleware was extracted from Express 2.x, after Express 3.x removed direct support for the flash. connect-flash brings this functionality back to Express 3.x, as well as any other middleware-compatible framework or application. +1 for radical reusability.

Install

$ npm install connect-flash

Usage

Express 3.x

Flash messages are stored in the session. First, setup sessions as usual by enabling cookieParser and session middleware. Then, use flash middleware provided by connect-flash.

var flash = require('connect-flash');
var app = express();

app.configure(function() {
  app.use(express.cookieParser('keyboard cat'));
  app.use(express.session({ cookie: { maxAge: 60000 }}));
  app.use(flash());
});

With the flash middleware in place, all requests will have a req.flash() function that can be used for flash messages.

app.get('/flash', function(req, res){
  // Set a flash message by passing the key, followed by the value, to req.flash().
  req.flash('info', 'Flash is back!')
  res.redirect('/');
});

app.get('/', function(req, res){
  // Get an array of flash messages by passing the key to req.flash()
  res.render('index', { messages: req.flash('info') });
});

Examples

For an example using connect-flash in an Express 3.x app, refer to the express3 example.

Tests

$ npm install --dev
$ make test

Credits

• Jared Hanson
• TJ Holowaychuk

License

The MIT License

Copyright (c) 2012-2013 Jared Hanson <http://jaredhanson.net/>