nodejs

9 Posts

Node.js is a free, cross-platform runtime that executes JavaScript outside the browser, created by Ryan Dahl in 2009. It's built on Google's V8 engine and uses an event-driven, non-blocking I/O model, which makes it efficient for handling many concurrent connections. Its npm registry is the largest package ecosystem available, and frameworks like Express and Nest simplify building servers and APIs. It's less suited to heavy CPU-bound work, since long computations block the main thread.

Why Node says ERR_MODULE_NOT_FOUND when the file exists

Node's ERR_MODULE_NOT_FOUND keeps firing when the file is right there. Every real cause, from missing extensions to broken package exports, plus the fix for each one.

Error: listen EADDRINUSE — Causes and Fixes

Node's 'listen EADDRINUSE: address already in use' means something already owns that port. Here's why, and the exact fixes for dev, watch mode, and Docker.

TypeError: "x" is not a function — Causes and Fixes

TypeError: x is not a function fires when you call a value that isn't callable — a typo, a lost `this`, or the wrong shape from an API. Here's how to fix each case.

Node.js: require is not defined in ES Module Scope

Fix Node's 'ReferenceError: require is not defined in ES module scope' and its __dirname sibling using createRequire and import.meta.

Node.js: Cannot Use Import Statement Outside a Module

Node.js's SyntaxError: Cannot use import statement outside a module still fires today, usually from "type": "commonjs". Here is the exact fix and why.

Node.js Error: Cannot Find Module — Causes and Fixes

Node's 'Error: Cannot find module' (MODULE_NOT_FOUND) explained frame by frame — why require() can't see your package and how to fix it for good.

Node.js ERR_MODULE_NOT_FOUND: Causes and Fixes

Node throws Error [ERR_MODULE_NOT_FOUND] when an ESM import can't be resolved — usually a missing file extension or directory index. Here's the exact fix.

UnhandledPromiseRejectionWarning: Causes and Fixes in Node.js

Why Node.js crashes with 'UnhandledPromiseRejectionWarning' or throws an uncaught exception, and how to fix and prevent unhandled promise rejections for good.

Cannot Read Properties of Undefined: Causes & Fixes

TypeError: Cannot read properties of undefined (reading 'x') explained across Chrome, Firefox, Safari, and Node — with the real fix, not just a null check.