Lecture 339:- Creating Flash Messages

Flash messages are messages that are displayed on a webpage, typically for a short period of time, in response to some user action or system event. They are often used to provide feedback to users after they have performed an action on a website, such as signing up or submitting a form.

In the context of a web application, flash messages can be created using server-side scripting languages such as Node.js or PHP. In Node.js, the most common way to create flash messages is to use middleware such as "connect-flash" or "express-flash" that can be integrated into an application's routing and rendering functions.

To create a flash message in Node.js, you typically first define the middleware in your application:

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const express = require('express'); const flash = require('connect-flash'); const app = express(); app.use(flash());

Once you have defined the middleware, you can create flash messages in your route handlers or controllers:

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app.post('/login', (req, res) => {  // do some login validation  if (/* validation fails */) {    req.flash('error', 'Invalid login credentials');    res.redirect('/login');  } else {    req.flash('success', 'Welcome back!');    res.redirect('/dashboard');  } });

In this example, the req.flash() function is used to create a flash message with a type of error or success, depending on whether the login validation succeeds or fails. The message itself is a string that describes the result of the validation.

After the flash message is created, it can be displayed on the webpage using a templating engine like EJS or Handlebars. For example, in an EJS template, you might include the following code to display the flash message:

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<% if (messages.success) { %>  <div class="alert alert-success"><%= messages.success %></div> <% } else if (messages.error) { %>  <div class="alert alert-danger"><%= messages.error %></div> <% } %>

In this code, the messages.success and messages.error properties are set automatically by the flash middleware, and they contain the flash messages that were created by the route handlers or controllers. The conditional statement checks which type of message was created and displays it accordingly.

By using flash messages, you can provide immediate feedback to users and enhance the user experience on your website or web application.