Packed vs Holey Arrays in V8: Why new Array(n) Makes Spread 4x Slower
V8 labels every array by what it holds and whether it may have gaps. Labels only get more general, and holey arrays take slower paths.
8 min read
Understand JavaScript, React & Next.js — one short post at a time.
Practical, diagram-first explanations you can read over coffee. 70 posts and counting.
Newest postNext.js use cache, cacheLife and cacheTag: How One View Counter Rebuilt Every Page
use cache stores a result, cacheLife decides when it goes stale, cacheTag lets you throw it out on demand. When to use each, and where TanStack Query fits.
8 min read
Read post →Latest
All 70 posts →How 'this' Works in JavaScript: Decided by the Call, Not the Code
'this' in JavaScript depends on how a function is called, not where it's written. Four rules and one arrow-function exception cover every case.
3 min read
turbopackRustReactCompiler: Running the React Compiler in Rust Inside Next.js
The React Compiler normally runs through Babel in Node.js. Next.js can run a Rust version inside Turbopack instead. Learn what that changes and what it saves.
4 min read
What Is Turbopack? How Next.js's Rust Bundler Avoids Doing Work Twice
Turbopack is the Rust bundler inside Next.js. Learn the one idea behind its speed, remembering every small step, and when you'll actually feel it.
5 min read
Bun vs npm, Yarn, Vite and Webpack: Who Does What in a JavaScript Kitchen
npm and Yarn fetch packages, Vite and webpack bundle code, Node runs it. Bun tries to do all of it. Learn which tool does which job.
6 min read
How SSR Works in React and Next.js: Built on the Server, Wired Up in the Browser
Server-side rendering in one picture: the server sends finished HTML, then hydration makes it interactive. Learn the steps, the gap between them, and why mismatches happen.
6 min read
JavaScript Classes Are Functions in a Costume (and What this.constructor Points To)
A JavaScript class is a function with stricter rules. Learn the three rules it adds and why this.constructor lets an object reach its own class.
4 min read
How Next.js Turns JSX and TypeScript Into Plain JavaScript
Browsers can't read JSX or types. See what the compiler erases, what it rewrites, and what actually reaches the browser in a Next.js app.
5 min read
Series
View all →Short posts on one theme, meant to be read in order. Each part stands alone, and together they build the full picture.
Get new posts in your inbox
One email when a new post is out: short, diagram-first explanations of JavaScript, React and Next.js. No spam, unsubscribe any time.