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Load Balancer Types — L4 vs L7
Layer-4 load balancers forward raw TCP/UDP packets based on IP and port; layer-7 load balancers terminate HTTP and route based on paths, headers and cookies — different trade-offs for different traffic.
4w ago cloud intermediate
Shadow DOM
A browser feature that attaches a scoped, encapsulated DOM subtree to an element — styles and IDs inside the shadow tree do not leak in or out, enabling true component isolation on the web.
4w ago frontend intermediate
Software Composition Analysis (SCA)
The practice and tooling for identifying all open-source and third-party components in a codebase, detecting known vulnerabilities (CVEs) in them, and flagging licence risks — distinct from static analysis of your own code.
4w ago security intermediate
Technical Writing for Developers
The craft of writing documentation, READMEs, design docs, RFCs, and comments clearly enough that another engineer can act on them without asking you — a force multiplier that most developers undertrain.
4w ago general beginner
Diagram: Covariance & Contravariance Covariance & Contravariance 4.7
Variance describes how subtype relationships on a type's components affect subtype relationships on the whole type — covariant types follow the direction, contravariant types reverse it.
1mo ago typescript advanced
Diagram: Discriminated Unions Discriminated Unions 2.0
A union of types that each carry a shared literal field (the discriminant) allowing TypeScript to narrow exhaustively — the canonical way to model mutually exclusive states.
1mo ago typescript intermediate
Diagram: Module Augmentation & Declaration Merging Module Augmentation & Declaration Merging 2.0
Module augmentation lets you extend third-party or global type definitions without modifying their source — adding properties to existing interfaces, modules, or the global scope.
1mo ago typescript advanced
Diagram: Recursive Types Recursive Types 3.7
Types that reference themselves to describe arbitrarily nested structures — trees, nested menus, JSON, linked lists — without requiring any escape hatch.
1mo ago typescript advanced
Diagram: Type Guards & Narrowing Type Guards & Narrowing 2.0
Type guards are expressions that narrow a union type to a more specific type at runtime — telling TypeScript exactly which branch of a union you're in.
1mo ago typescript intermediate
async / await in JavaScript ES2017
async functions always return a Promise; await pauses execution inside an async function until a Promise settles — giving asynchronous code the readability of synchronous code without blocking the event loop.
1mo ago javascript intermediate
Brute-Force Protection
Defences against automated credential-guessing attacks — rate limiting login attempts, account lockout, CAPTCHA, and multi-factor authentication to make guessing passwords computationally infeasible.
CWE-307 OWASP A7:2021
1mo ago security intermediate
ES Modules (ESM) ES2015
The official JavaScript module system — import and export statements enable static dependency graphs, tree-shaking, and native browser module loading without a bundler.
1mo ago javascript intermediate
Fetch API ES2015
The browser-native Promise-based API for making HTTP requests — replacing XMLHttpRequest with a cleaner interface supporting streaming, CORS, and request/response objects.
1mo ago javascript beginner
HTTP Cookies in PHP PHP 7.3+
Cookies are small key-value pairs sent by the server via Set-Cookie and echoed back by the browser on every request — PHP sets them with setcookie() before any output, with Secure, HttpOnly, and SameSite flags controlling safety.
1mo ago php beginner
Insecure Deserialization
Deserializing attacker-controlled data can trigger arbitrary object construction and method calls — PHP's unserialize() with untrusted input enables remote code execution via gadget chains in the loaded class graph.
CWE-502 OWASP A8:2021
1mo ago security advanced
Memory Management in JavaScript
JavaScript uses automatic garbage collection — the engine reclaims memory when objects are no longer reachable. Memory leaks occur when references are unintentionally retained, preventing collection.
1mo ago javascript intermediate
OAuth 2.0
An authorisation framework that lets users grant third-party applications limited access to their resources without sharing passwords — using short-lived access tokens issued via defined flows for different client types.
CWE-287 OWASP A7:2021
1mo ago security intermediate
Timing Attacks
Side-channel attacks that infer secret values by measuring how long an operation takes — a string comparison that short-circuits on the first mismatch leaks information about the secret one character at a time.
CWE-208
1mo ago security advanced
Canonical URL (rel=canonical)
A <link rel='canonical'> tag that tells search engines which URL is the authoritative version of a page — preventing duplicate content from splitting ranking signals across multiple URLs.
1mo ago frontend intermediate
Core Web Vitals
Google's three field-measured performance metrics — LCP (loading), INP (interactivity), CLS (visual stability) — used as direct search ranking signals since 2021.
1mo ago performance intermediate
✓ schema.org compliant