Node JS

Node.js is a server-side JavaScript execution context. Because of its speed and scalability, it allows developers to write client-side logic in JavaScript and use that same code server-side.

Key features of Node.js are its non-blocking, event-driven architecture, asynchronous programming, and the capability to handle several requests at the same time, making it suitable for developing huge scalable applications.

While Node.js is asynchronous with server-side JavaScript, traditional server-side languages, like PHP, are synchronous, meaning requests are processed as they come, one by one.

The event loop of Node.js is a method under which Node.js can accept multiple requests without getting blocked, thus making it very efficient in handling I/O operations, such as reading files or handling requests.

Modules in Node.js are small reusable codes that can be used in the application for organizing your application. You can use built-in, out-of-the-box modules like http or build your custom module for the specific functionality that you would like to manage.

A package manager associated with node.js is known as npm, which makes it very easy for a developer to install and manage third-party libraries and packages that can be integrated into their applications, thereby simplifying the process of creating applications.

Node.js handles multiple requests via an event-driven, non-blocking I/O model, meaning it does not wait for the completion of one request before starting to process the subsequent one. This makes it much more efficient in processing requests.

Express.js is nothing but an application layer for Node.js. It makes the routing, middleware, and requests management much simpler and thereby easy with Node.js to develop web applications and APIs.

Simply put, middleware is a function that runs when the request comes and when the response goes in an Express.js application. The request data can be altered, and error handling or any function can be implemented before sending the final response.

Errors are handled in Node.js by try-catch-exception blocks, along with appropriate event listeners for capturing unhandled exceptions. Such an architecture helps to keep the application running without glitches.