Node.js is a runtime environment that allows you to execute JavaScript code on the server side. It’s built on the V8 JavaScript runtime engine, the same engine that powers the Google Chrome browser. Node.js enables the development of scalable, high-performance, and networked applications.
Key Features of Node.js:
Non-blocking I/O:
- Node.js is designed to be non-blocking and event-driven, making it efficient for handling concurrent operations. It uses an event loop to handle multiple requests without blocking the execution of other tasks.
Single Threaded:
- While the JavaScript code runs in a single thread, Node.js can handle concurrent operations by using non-blocking I/O operations and delegating tasks to the operating system.
Asynchronous Programming:
- Node.js relies heavily on asynchronous programming to handle a large number of concurrent connections efficiently. This is achieved through callback functions, Promises, and async/await.
V8 JavaScript Engine:
- Node.js is built on the V8 JavaScript engine, which compiles JavaScript code to native machine code for improved performance.
NPM (Node Package Manager):
- NPM is the default package manager for Node.js, providing a vast ecosystem of reusable modules and libraries. Developers can easily install, manage, and share dependencies using NPM.
Cross-platform:
- Node.js is cross-platform and can run on various operating systems, including Windows, macOS, and Linux.
Node.js Architecture:
1. Event Loop:
- The event loop is at the core of Node.js architecture. It enables the handling of multiple connections simultaneously without blocking the execution of other tasks. The event loop continuously checks for events and executes callbacks associated with those events.
2. Callback Queue:
- Asynchronous operations in Node.js are managed through callbacks. When an asynchronous operation completes, its callback is added to the callback queue.
3. Event Emitters:
- Many objects in Node.js are instances of event emitters. These objects emit events, and developers can register listeners to handle these events. Events and event emitters play a crucial role in building scalable and event-driven applications.
4. Libuv:
- Libuv is a cross-platform library that provides the event loop implementation and handles I/O operations. It abstracts the differences in I/O operations between different operating systems.
5. Modules:
- Node.js follows a modular approach, allowing developers to organize their code into reusable modules. Each module encapsulates its functionality, making it easier to maintain and scale applications.
6. NPM (Node Package Manager):
- NPM is a package manager for Node.js that simplifies the process of installing, sharing, and managing dependencies. It also provides a command-line interface for various tasks related to package management.
7. Node.js Core Modules:
- Node.js comes with a set of core modules that provide essential functionalities. These modules include
httpfor handling HTTP requests,fsfor file system operations,eventsfor event-driven programming, and more.
8. Buffers and Streams:
- Buffers and streams are important concepts in Node.js for handling binary data efficiently. Buffers are used to work with binary data directly, while streams allow the processing of data in chunks, reducing memory consumption.
9. Child Processes:
- Node.js allows the creation of child processes to run parallel tasks. This is particularly useful for executing external commands, running scripts in different languages, or parallelizing tasks.
10. Middleware:
- In the context of web applications, Node.js often uses middleware for handling requests and responses. Middleware functions can be used to perform tasks such as authentication, logging, and error handling.