ECMAScript Modules (ESM) is the official standard module system for JavaScript, introduced in ES2015. Where CommonJS was designed specifically for Node.js, ESM was designed for the language itself, intended to work in browsers, Node.js, Deno, and any other JavaScript runtime. It uses import and export statements instead of require() and module.exports, and its static structure…
Every Node.js file is a module. When you write code in a .js file and run it with Node.js, the runtime wraps that code in a function before executing it. This wrapper provides the require, module, and exports variables that make the module system work. Understanding this mechanism is essential because it explains how code…
Node.js provides a set of global objects available in every module without requiring an import statement. These globals form the runtime environment’s foundation, offering access to the current process, console output, binary data handling, and timing functions. Unlike browser JavaScript where the global object is window, Node.js uses global (or the modern globalThis), but with…
Node.js installation is straightforward, but the choice of tooling matters more than the installation itself. Installing Node.js directly from the official website or a distribution package manager works for simple cases, but it creates a single, system-wide version that is difficult to change. Modern Node.js development almost always involves multiple projects that require different Node.js…
Node.js is a runtime environment that allows JavaScript, traditionally confined to the browser, to run on the server. It was created by Ryan Dahl and first released in 2009, built on Chrome’s V8 JavaScript engine. The core idea is simple: take the V8 engine that Google developed for Chrome, embed it in a C++ program,…
Docker Engine does not install the same way on every operating system, and the differences are not cosmetic. On Linux, Docker Engine runs natively as a daemon that talks directly to the kernel’s namespaces and cgroups. On macOS, Docker Engine cannot run natively because macOS is not Linux — it has no namespaces and no…
Namespaces isolate what a container can see. Control groups determine how much of each resource it can use. These two kernel features are complementary and together they form the complete foundation of containerization. Without cgroups, a single container running a runaway process could consume all available memory on the host, saturate every CPU core, or…
Linux namespaces are the kernel feature that makes containers possible. A namespace wraps a global system resource in an abstraction that makes it appear to processes within the namespace that they have their own isolated instance of that resource . Changes made by one process inside a namespace are visible to other processes that are…
Docker presents itself as a single command, but behind that command lies a layered architecture of cooperating processes. The Docker CLI you type into is only the outermost layer, a thin client that translates your input into API calls. Those calls reach the Docker daemon, which handles Docker-specific concerns like networking and volumes before delegating…
Containerization is the practice of packaging an application together with all its dependencies — libraries, runtime, system tools, and configuration — into a single, portable unit that can run consistently across any environment. Docker, released in 2013, did not invent this concept, but it standardized the tooling and workflow in a way that made containers…