What are Angular Signals?
Angular Signals is a new feature in Angular 16 that allows you to develop reactive code in a new way. Signals are a reactive primitive, which implies they can alert their dependents when their value changes. This makes them suitable for use in reactive applications, where it is critical to be able to automatically adjust the UI in reaction to data changes.

To begin with Angular Signals, import the Signals module from the @angular/core package. The signal() method is then used to create a signal. This function takes two arguments: the signal's initial value and an options object. The options object is used to determine whether the signal is written or read-only, as well as other parameters.

The subscribe() function
You can subscribe to a signal after you've produced it with the subscribe() method. As an argument, this method accepts a function that will be called whenever the signal changes. You can also use the unsubscribe() method to unsubscribe from a signal.

Signals can be utilized to construct a wide range of reactive patterns. You can, for example, use a signal to represent a component's state and then subscribe to the signal to update the UI whenever the state changes. Signals can also be used to provide two-way data coupling between components.

Here's a simple demonstration of how to use Angular Signals.
import { Signals } from '@angular/core';

export class MyComponent {
  count = new Signals<number>(0);

  increment() {
    this.count.value++;
  }

  decrement() {
    this.count.value--;
  }

  constructor() {
    this.count.subscribe(value => {
      // Update the UI here
    });
  }
}

In this case, we'll build a signal to indicate the current count. Then, we subscribe to the signal so that the UI may be updated anytime the count changes. Angular Signals have several advantages over alternative methods of developing reactive Angular programs. They are more granular than observables, for example, and can be used to track changes to individual values or states. They are also more synchronous, which makes them easier to debug and comprehend.

Overall, Angular Signals is a potent new tool for writing more reactive and efficient Angular programs.

Benefits of using Angular Signals
Here are some of the benefits of using Angular Signals.

• Granular updates: Angular Signals allow you to track changes to specific values or states rather than having to track changes to entire observables. This can lead to more efficient change detection and faster updates to the UI.
• A new reactive primitive: Angular Signals are a new reactive primitive, which means that they can be used to implement a variety of different reactive patterns in a simple and straightforward way.
• Simplified framework: Angular Signals simplify the Angular framework by providing a unified way to represent and track reactive values. This makes it easier to write and maintain reactive Angular code.
• No side effects: Angular Signals are designed to be pure, which means that they do not have any side effects. This makes them easier to reason about and debug.
• Automatic dependency tracking: Angular Signals automatically track their dependencies, so you don't have to worry about manually unsubscribing from them. This can help to prevent memory leaks and improve the overall performance of your application.

If you are writing reactive Angular code, I encourage you to try using Angular Signals. They are a powerful new tool that can make your code more efficient, simpler, and more reliable.

In this article, we'll look at how to use Node.js to create a web application. Let's take it one step at a time.

Step 1: Download NodeJS from the NodeJS website.
Download the Windows Installer from the Nodejs website. Check that you have the most recent version of NodeJs. It comes with the NPM package management. Install node js already and skip the preceding step.

Step 2: Ensure that Node and NPM are installed and that their PATHs are configured.
Check If you're not sure whether you installed everything correctly, use "Command Prompt" to double-check.

To verify the installation and confirm whether the correct version was installed,

Enter the following command to Check the node version.
Node --version or Node -v

Check the npm version, and run this command:
npm --version or npm -v

Step 3. Create a new project
You can create a project folder wherever you want on your computer and name it whatever you want.

Step 4. Create a new js file
Create a .js File By using the .js file extension

I Create an app.js file in the project folder. Create a simple string variable in app.js and send the contents of the string to the console: save the file.
var message= “Hi C# Corner”;
console.log(message);

Step 5. Run the App
It's simple to run app.js with Node.js. From a terminal, just type: Node .\app.js

You can see the "Hi C# Corner" output to the terminal, and then Node.js returns

Step 6. Install NPM Packages
install npm package Go to the terminal and type npm init -y this command line, we highlight -y when we install in npm' npm init' Does that time ask a question: package name? We can give the package name as yourself. Otherwise, it takes the default name Project Folder Name. If entered, the command line npm init -y takes the saver name as the default.

I'm going to run this Project in package.js, So I have to add a line in scripts at package.js "serve": "node app.js".
"scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "serve": "node app.js"
  },

I'm going to run the application with this command npm run serve.

What Is Express JS?    
Express is a node js web application framework that provides broad features for building web and mobile applications. It is used to build a single page, multipage, and hybrid web application.

Features of Express Framework
Allows to set up middlewares to respond to HTTP Requests.
Defines a routing table that is used to perform different actions based on HTTP Method and URL.
Allows to dynamically render HTML Pages based on passing arguments to templates
npm install express or npm i express

I recommend the nodemon package for Node. js-based applications by automatically restarting the node application when the file changes in the directory are detected.

nodemon will be installed globally on your system path.
npm install -g nodemon # or using yarn: yarn global add nodemon

Step 8. Write down the following code in the app.js file
const express = require("express");
const app = express();
const port = 3000;

//routes
app.get("/", (req, res) => {
  res.send("HI C# Corner!");
});


app.listen(port, () => {
  console.log(`My Sample Nodejs App Listening On Port ${port}`);
});

Following is a very basic Express app that starts a server and listens on port 3000 for the connection.
app.listen(port, () =>
{console.log(`My Sample Nodejs App Listening On Port ${port}`)
})

The app responds with "HI C# Corner!" for requests to the root URL (/) or route.
app.get('/', (req, res) => {
  res.send('HI C# Corner!')
})

`npm run serve`

This app starts a server and listens on port 3000 for connections.

Step 9. Now you can see the output on your browser
Now go to http://localhost:3000/ in the browser, and you will see the following output:

In this article, we will learn how to create a Node project and how we can develop a web application using Node.js. It is a runtime environment and library for running JavaScript code outside the browser. It must be installed on the system by downloading the software from the Node.js website and setting the path in the environment variables section.