Express 4 split built-in middlewareSoftware between applications and lower-level systems — handles integration, messaging, or shared services. into separate packages and fixed the router — the version that powered the MEAN stack and early RESTRepresentational State Transfer — a style for web APIs using HTTP methods and resource URLs. microservicesAn architecture splitting applications into small independent services — each deployed and scaled separately.. Most NodeNode.js — JavaScript on the server via an event-driven runtime built on V8. tutorials and boilerplates still trace back to Express 4's APIApplication programming interface — a defined way for programs to talk to each other or to a service. surface.

Express 4 was the stable baseline for NodeNode.js — JavaScript on the server via an event-driven runtime built on V8. web APIs through the 2010s.

A cleaner router and middlewareSoftware between applications and lower-level systems — handles integration, messaging, or shared services. model defined how NodeNode.js — JavaScript on the server via an event-driven runtime built on V8. handles HTTPHyperText Transfer Protocol — the protocol browsers use to request and receive web pages..