Topic
91 posts tagged “JavaScript”.
Takina · · 4 min read Abstract classes in TypeScript define shared implementation plus methods subclasses must fill in. How they differ from interfaces and when to reach for them.
Takina · · 3 min read React Suspense lets components pause rendering while they wait on async data, showing a fallback UI instead of manual loading-state juggling.
Takina · · 4 min read A lockfile records the exact dependency versions your package manager resolved, so every install — from your laptop to CI — reproduces the same tree.
Takina · · 3 min read never represents values that can't exist — it marks unreachable code, exhaustive switches, and functions that always throw or loop forever.
Takina · · 4 min read TypeScript's readonly keyword blocks reassignment at compile time for properties, arrays, and tuples — with no runtime enforcement at all.
Takina · · 4 min read The Intl API formats dates, numbers, and currency using a user's locale without a library. How Intl.DateTimeFormat and Intl.NumberFormat work.
Takina · · 4 min read requestIdleCallback runs low-priority JavaScript when the browser is idle, without blocking rendering, input, or the main thread.
Takina · · 5 min read Turbopack is a Rust-based bundler built for incremental speed; Webpack is the mature, plugin-heavy standard. How they differ and when to pick each.
Takina · · 5 min read Promise.all() fails fast, allSettled() waits for every result, and race() returns whichever promise finishes first — how to choose correctly.
Takina · · 4 min read JavaScript's dynamic import() loads a module on demand and returns a promise, letting you split bundles and defer code until it's actually needed.
Takina · · 4 min read The spread operator (...) expands an iterable into individual elements; the rest operator collects elements back into an array. Same syntax, opposite jobs.
Takina · · 4 min read TypeScript's as const assertion locks a value to its literal, readonly type instead of widening it. How it works and when to reach for it.
Takina · · 4 min read The ResizeObserver API lets JavaScript watch an element's box size and react without polling or resize-event hacks. How it works and when to use it.
Takina · · 5 min read A JavaScript memory leak happens when a reference outlives its usefulness and the garbage collector can't reclaim it. Common causes and how to find them.
Takina · · 4 min read localStorage, sessionStorage, and cookies all store data in the browser, but differ in lifetime, size limits, and whether the server can see them.
Takina · · 4 min read Import maps let browsers resolve bare module specifiers like "react" to real URLs, enabling native ES module imports without a bundler.
Takina · · 5 min read The Push API lets a web app send notifications through a service worker, even when the site isn't open in a browser tab. Here's the full flow.
Takina · · 5 min read JavaScript destructuring unpacks values from arrays and objects into variables in one expression. How it works, with the rest and spread operators.
Takina · · 4 min read How JavaScript determines what this refers to: default, implicit, explicit, and new binding, plus why arrow functions behave differently.
The Lycoris Team · · 4 min read A monad is a wrapper type with rules for chaining operations that might fail, be async, or carry extra context — like Promise or Optional, generalized.
Takina · · 5 min read Type guards are functions and checks that narrow a TypeScript union to a specific type at runtime. How typeof, instanceof, in, and custom guards work.
Takina · · 4 min read TypeScript function overloads let one function name accept multiple call signatures with different types. How overload signatures work and when to use them.
Takina · · 4 min read Tagged template literals let a function intercept a template string's parts before interpolation — the mechanism behind safe SQL, styled-components, and i18n.
Takina · · 5 min read IndexedDB is a browser API for storing large amounts of structured data client-side, with indexes, transactions, and no size limit like localStorage.
Takina · · 4 min read Event delegation attaches one listener to a parent instead of one per child, using event bubbling to catch clicks from elements added after page load.
Takina · · 4 min read The Intersection Observer API tells you when an element enters or leaves the viewport, without scroll-event polling. How it works and where to use it.
Takina · · 4 min read structuredClone() is a built-in JavaScript function for deep-copying values, including cycles and typed arrays, without the workarounds JSON tricks require.
Takina · · 4 min read tsconfig.json controls how TypeScript checks and compiles your code. Here are the options that actually change behavior, and the ones you can leave alone.
Takina · · 4 min read Template literal types let TypeScript build string types from other types, like JavaScript template strings. How they work, with practical patterns.
Takina · · 4 min read The Fetch API is JavaScript's built-in interface for making HTTP requests. How it works, its promise-based flow, and where it trips people up.
Takina · · 4 min read TypeScript's interface and type both describe object shapes, but they diverge on declaration merging, unions, and extension. When to reach for each.
Takina · · 4 min read requestAnimationFrame schedules a callback right before the browser repaints, syncing JavaScript animation to the display's refresh rate. How it works.
Takina · · 4 min read Solid.js uses fine-grained signals and no virtual DOM; React re-renders components and diffs. How the two reactivity models differ in practice.
Takina · · 5 min read SSE streams one-way updates over plain HTTP; WebSockets open a full-duplex channel. How they differ and which fits your real-time feature.
Takina · · 4 min read Mapped types transform one type into another by iterating over its keys — the mechanism behind Partial, Readonly, Record, and Pick under the hood.
Takina · · 4 min read TypeScript enums group named constants under one type. How numeric, string, and const enums compile, and when a union type is the better choice.
Takina · · 4 min read A JavaScript Symbol is a guaranteed-unique primitive used for collision-free object keys. How Symbols work, well-known Symbols, and when to use them.
Takina · · 4 min read A discriminated union tags each variant of a type with a shared literal field, letting TypeScript narrow the type automatically inside a switch or if check.
Takina · · 4 min read var, let, and const differ in scope, hoisting behavior, and reassignment rules. Here's what each one actually does and when to reach for it.
Takina · · 4 min read ESLint catches bugs and enforces code patterns; Prettier only reformats how code looks. Why most JavaScript projects run both, not one or the other.
Takina · · 4 min read Optional chaining (?.) short-circuits on null or undefined instead of throwing; nullish coalescing (??) supplies a default only for null or undefined.
Takina · · 4 min read Prototypal inheritance means JavaScript objects inherit properties directly from other objects via a prototype chain, not from classes. How it works.
Takina · · 4 min read Web workers run scripts off the main thread for parallel computation. Service workers intercept network requests for offline and caching. How they differ.
Takina · · 4 min read map, filter, and reduce transform arrays without loops or mutation. How each one works, when to reach for it, and where they trip people up.
Takina · · 4 min read TypeScript's unknown forces a type check before use; any opts out of type checking entirely. When to reach for each in real code.
Takina · · 4 min read A source map is a file that maps minified, bundled, or transpiled code back to its original source, so debuggers and stack traces stay readable.
Takina · · 4 min read Conditional types let TypeScript pick a type based on another type, using T extends U ? X : Y — the foundation of most advanced type utilities.
Takina · · 3 min read Currying transforms a multi-argument function into a chain of single-argument functions. How currying and partial application work in JavaScript.
Takina · · 4 min read Vue uses a template syntax with a reactive proxy system; React uses JSX with a virtual DOM. How the two frameworks differ and when to pick each.
Takina · · 4 min read Node.js streams process data in chunks instead of loading it all into memory. How readable, writable, and transform streams work, and when to reach for them.
Takina · · 5 min read A WeakMap holds object keys without blocking garbage collection, unlike a regular Map. How WeakMap and WeakRef work and when to reach for them.
Takina · · 4 min read JavaScript's Map and Set are built-in collections with cleaner semantics than plain objects and arrays. Here's how each works and when to reach for one.
Takina · · 4 min read The Temporal API is JavaScript's built-in replacement for Date — immutable, timezone-aware objects for dates, times, and durations.
Takina · · 4 min read TypeScript's satisfies operator checks a value against a type without widening or erasing its inferred literal type. Here's when to reach for it.
Takina · · 4 min read TypeScript decorators attach reusable behavior to classes and members with an @ syntax. How class, method, and field decorators work, with real examples.
Takina · · 4 min read Shadow DOM attaches an isolated DOM tree to an element so a component's styles and markup can't leak in or out. Here's how it actually works.
Takina · · 4 min read npm, pnpm, and Yarn all install the same packages but differ in speed, disk usage, and monorepo support. Here's how to pick the right one.
Takina · · 4 min read AbortController lets JavaScript cancel an in-flight fetch or async task on demand, preventing stale responses from overwriting newer state.
Takina · · 5 min read ESM and CommonJS are JavaScript's two module systems — how import/export differs from require/module.exports, and when each one is used.
Chisato · · 3 min read Cross-site scripting (XSS) injects malicious scripts into pages other users view. How stored, reflected, and DOM-based XSS work, and how to prevent them.
Takina · · 4 min read Optimistic UI updates the interface immediately, before the server confirms a change, then rolls back if the request fails — for apps that feel instant.
Takina · · 4 min read Web Components are browser-native APIs for building reusable, encapsulated custom elements that work in any framework, or none at all.
Takina · · 4 min read TypeScript utility types like Partial, Pick, Omit, and Record transform existing types instead of redeclaring them. How the common ones work, with examples.
Takina · · 4 min read A monorepo holds multiple projects in one repository with shared tooling and atomic commits. How it compares to splitting projects across separate repos.
Takina · · 4 min read Generators are functions that pause and resume with the yield keyword, producing values lazily on demand instead of computing them all at once.
The Lycoris Team · · 4 min read Memoization caches a function's return value by its input, skipping recomputation on repeat calls. How it works and when it actually helps.
Takina · · 4 min read TypeScript generics let functions and types work with any type while preserving the specific type used at each call site, avoiding both duplication and any.
Takina · · 4 min read Async/await is syntactic sugar over Promises, not a different mechanism. How each looks in practice, and when to still reach for raw Promises.
Takina · · 4 min read The virtual DOM is an in-memory copy of the UI tree that frameworks diff against the previous version to batch and minimize real DOM updates.
Chisato · · 4 min read A Content Security Policy is an HTTP header that restricts what scripts and resources a page can load, blocking most XSS attacks by default.
Takina · · 4 min read A JavaScript Proxy wraps an object and intercepts operations like get and set through traps. How traps work, with practical examples and Reflect.
Takina · · 4 min read A web worker runs JavaScript on a background thread, freeing the main thread to keep the UI responsive. How workers communicate and when to use one.
Takina · · 5 min read Svelte compiles away at build time; React ships a runtime and virtual DOM. Bundle size, reactivity model, and ecosystem tradeoffs compared.
Takina · · 5 min read Microsoft shipped TypeScript 7.0 with a Go-native compiler that's roughly 10x faster than 6.0. What changed, what breaks, and how to upgrade.
Takina · · 4 min read Tree shaking removes unused exports from a JavaScript bundle at build time, shrinking file size by relying on ES module static structure.
Takina · · 5 min read A JavaScript closure is a function that remembers the variables from where it was defined. How closures work, why they matter, and the classic loop gotcha.
Takina · · 5 min read Debounce and throttle both tame rapid-fire events, but differently — debounce waits for a pause, throttle enforces a steady rate. When to use each.
Takina · · 3 min read htmx lets you build dynamic, interactive pages with HTML attributes — no SPA, no build step. Learn the core ideas and ship a working live-search example in minutes.
Takina · · 4 min read WebRTC lets browsers stream audio, video, and data directly between peers — no plugins. How getUserMedia, RTCPeerConnection, and ICE/STUN/TURN fit together.
Takina · · 5 min read Static sites don't need a search server. Learn how Pagefind indexes your HTML at build time and adds fast, client-side full-text search for free.
Takina · · 4 min read A WebSocket is a protocol for full-duplex, persistent communication over a single TCP connection. Learn how it works, when to use it, and what the alternatives are.
Takina · · 4 min read CORS lets a server opt in to cross-origin browser requests, relaxing the same-origin policy in a controlled way. Why it exists and how to fix CORS errors.
Takina · · 4 min read JavaScript is single-threaded, yet pages stay responsive. A clear tour of the call stack, task queue, and microtasks — with examples you can run.
Takina · · 5 min read Signals offer fine-grained reactivity with automatic dependency tracking — and nearly every major framework has adopted them. Here's why the model won.
Takina · · 4 min read The View Transitions API brings smooth, app-like transitions to the web without a heavy SPA framework. Here's how it works and how to use it today.
Takina · · 5 min read An honest comparison of Bun and Node.js in 2026 — speed, ecosystem, built-in tooling, and when each runtime actually wins.
Takina · · 3 min read JavaScript is the programming language that makes web pages interactive. Learn how it works alongside HTML and CSS, and why it runs nearly everywhere.
Takina · · 5 min read React Server Components render exclusively on the server and stream a serialized result — no client JS shipped for that component. Here's what that actually means.
Takina · · 4 min read The DOM is the live in-memory tree browsers build from your HTML, which JavaScript reads and manipulates. Learn how it works and why it matters.
Takina · · 3 min read TypeScript adds a safety net to JavaScript without slowing you down. Here's how to set it up, the handful of concepts that matter, and how to adopt it gradually.
Takina · · 4 min read Server-Sent Events stream real-time updates over a single HTTP connection. How SSE works, when to use it, and how it compares to WebSockets.
