Node.js Process Complete Reference

A process object is a global object that gives information about and controls the node.js process. As it is global, it can be used in the project without importing it from any module. 

Understanding Node.js Processes

Single-threaded Event Loop

Node.js operates on a single-threaded event loop architecture, allowing it to handle concurrent operations efficiently without the need for multi-threading.

Process Object

The process object in Node.js provides information and control over the Node.js process. It includes properties like process.pid (process ID), process.argv (arguments passed to the process), and process.env (environment variables).

Child Processes

Node.js allows for the creation of child processes to execute external commands or run additional Node.js scripts asynchronously. This enables parallel processing and improves performance.

Events and Event-driven Architecture

EventEmitter Class

The EventEmitter class in Node.js facilitates event-driven programming by allowing objects to emit named events asynchronously. Developers can create custom events and define listeners to handle them.

Core Events

Node.js core modules, such as HTTP, File System, and EventEmitter, utilize event-driven architecture extensively. Understanding core events and their event emitters is essential for building Node.js applications.

Execution Models and Asynchronous Programming

Non-blocking I/O

Node.js employs non-blocking, asynchronous I/O operations, enabling it to handle multiple requests concurrently without waiting for previous operations to complete. This improves application responsiveness and scalability.

Callbacks

Callbacks are a common pattern in Node.js for handling asynchronous operations. Functions accept callbacks as arguments, which are executed once the operation completes. However, callback-based code can lead to callback hell and make code hard to maintain.

Promises

Promises provide a cleaner alternative to callbacks for managing asynchronous operations in Node.js. They represent the eventual completion or failure of an asynchronous operation and allow chaining of multiple asynchronous tasks.

Async/Await

Introduced in ES2017, async/await syntax simplifies asynchronous code in Node.js by allowing developers to write asynchronous code in a synchronous style. It enhances code readability and reduces the complexity associated with nested callbacks or promise chains.

Example:

// Node.js program to demonstrate the // process.versions property // Include process module const process = require('process'); // Printing process.versions property value // and variable count let no_versions = 0; // Calling process.versions property const versions = process.versions; // Iterating through all returned data for (let key in versions) {  // Printing key and its versions  console.log(key + ":\t\t\t" + versions[key]);  no_versions++; } // Printing count value console.log("Total no of values available = " + no_versions); 

Output:

http_parser: 2.8.0
node: 10.16.0
v8: 6.8.275.32-node.52
uv: 1.28.0
zlib: 1.2.11
brotli: 1.0.7
ares: 1.15.0
modules: 64
nghttp2: 1.34.0
napi: 4
openssl: 1.1.1b
icu: 64.2
unicode: 12.1
cldr: 35.1
tz: 2019a
Total no of values available = 15

The Complete List of Processes is listed below: