Programming

JavaScript manages memory for you. You create objects, arrays, and closures — and the engine reclaims them when they’re no longer needed. That’s the deal. In exchange, you can’t manually free memory, and you can’t force garbage collection. But you can create leaks, and you can prevent them. Understanding how garbage collection works isn’t about…

Some events fire hundreds of times per second. Scroll, resize, mousemove, input — the browser doesn’t wait for the user to pause; it fires a callback on every change. If your handler does real work, that’s hundreds of times more work than necessary. Debounce and throttle are the two patterns that fix this. They both…

Testing is how you prove your code works — and how you keep it working as it changes. Without tests, every edit is a gamble. With tests, you can refactor confidently, catch regressions immediately, and document what the code is supposed to do. JavaScript has a mature testing ecosystem, and the concepts are the same…

For most of JavaScript’s life, it ran only in the browser. Node.js changed that. It takes the V8 engine — the same one inside Chrome — and wraps it with an environment that can read files, open sockets, spawn processes, and run on servers. Suddenly JavaScript could do what PHP, Python, and Ruby did. Node…

Every Node project has a package.json. It’s the manifest — the file that describes your project, lists its dependencies, and defines scripts. Around it, a package manager installs, updates, and resolves those dependencies. Three tools dominate the ecosystem: npm, yarn, and pnpm. They do the same job with different trade-offs. Understanding package.json and how the…

JavaScript doesn’t stop moving. Every year, TC39 ships new features — some big, some small, all designed to remove boilerplate and fix sharp edges. Between ES2022 and the latest proposals, a set of methods and syntax has landed that most developers haven’t caught up with yet. This chapter covers what’s actually in the language now,…

Large numbers are hard to read. 1000000000 and 100000000 look almost identical at a glance — one is a billion, the other is a hundred million, and the human eye can’t reliably tell them apart. Numeric separators fix this: an underscore you place wherever you want, that JavaScript ignores entirely. The feature is small. It…

Before ES2022, await only worked inside async functions. To use it at the module’s top level, you had to wrap everything in an async IIFE — a workaround that added noise to every file that needed to fetch config, load a database connection, or initialize resources before exporting anything. Top-level await changes that. In an…