The difference between node.js and express.js in the level of abstraction:

-> Node.js is a platform for building server-side event-driven i/o application using javascript.

-> Express.js is a framework based on node.js for building web-application using principles and approaches of node.js

NodeJS

Node.js takes a different approach. It runs a single-threaded event loop registered with the system to handle connections, and each new connection causes a JavaScript callback function to fire. The callback function can handle requests with non-blocking I/O calls, and if necessary can spawn threads from a pool to execute blocking or CPU-intensive operations and to load-balance across CPU cores. Node’s approach to scaling with callback functions requires less memory to handle more connections than most competitive architectures that scale with threads, including Apache HTTP Server, the various Java application servers, IIS and ASP.NET, and Ruby on Rails.

Node.js turns out to be quite useful for desktop applications in addition to servers. Also note that Node applications aren’t limited to pure JavaScript. You can use any language that transpiles to JavaScript, for example TypeScript and CoffeeScript. Node.js incorporates the Google Chrome V8 JavaScript engine, which supports ECMAScript 2015 (ES6) syntax without any need for an ES6-to-ES5 transpiler such as Babel.

#programming #nodejs #expressjs #javascript #es6