Dictionary

GitHub Actions is a CI/CD and workflow automation platform built directly into GitHub. Developers define workflows in YAML files that trigger on events like pushes, pull requests, or schedules, running jobs on GitHub-hosted or self-hosted runners. Its marketplace offers thousands of reusable actions for tasks like linting, testing, deploying, and publishing packages.

GitOps is an operational model where Git repositories serve as the single source of truth for both application code and infrastructure configuration. Automated agents like ArgoCD or Flux continuously monitor the repo and synchronize the live environment to match the declared state. Every change goes through pull requests, providing a full audit trail and enabling rollbacks by simply reverting a commit.

In AI, hallucination refers to when a language model generates confident-sounding but factually incorrect or fabricated information. This occurs because LLMs predict statistically likely text rather than retrieving verified facts. Mitigation strategies include RAG, grounding responses in source documents, structured output validation, and using temperature settings to reduce creative deviation.

Headless UI refers to component libraries that provide behavior, state management, and accessibility logic without any predefined styling or markup. Libraries like Radix Primitives, Headless UI by Tailwind Labs, and React Aria give developers full control over visual presentation while handling complex patterns like focus management, keyboard navigation, and ARIA attributes. This approach decouples functionality from design, making it ideal for custom design systems.

Hermes is an open-source JavaScript engine developed by Meta, optimized specifically for running React Native applications on mobile devices. It uses ahead-of-time (AOT) compilation to convert JavaScript into bytecode during the build process, resulting in faster app startup times, reduced memory usage, and smaller app sizes compared to JavaScriptCore. Hermes is now the default JavaScript engine for React Native and also supports iOS since React Native 0.70.

A Higher-Order Component (HOC) is an advanced React pattern where a function takes a component as input and returns a new enhanced component with additional props or behavior. Common use cases include adding authentication checks, analytics tracking, or data fetching logic to existing components. While HOCs were a primary code reuse pattern in class-based React, custom hooks have largely replaced them in modern functional component code due to their simpler composition model.

Hot reload is a development feature that injects updated code into a running application without restarting it or losing the current state. In Flutter, hot reload works by injecting updated Dart source code into the running Dart VM, typically completing in under a second. React Native offers a similar feature called Fast Refresh that preserves component state during edits. Both dramatically accelerate the development feedback loop compared to traditional compile-and-restart cycles.

Hydration is the process where a client-side JavaScript framework attaches event listeners and interactivity to server-rendered HTML markup. After the server sends pre-rendered HTML for fast initial display, the framework "hydrates" it by reconciling its virtual representation with the existing DOM and making it interactive. Hydration can be expensive on complex pages, which has led to innovations like partial hydration, progressive hydration, and React's selective hydration with Suspense.

Idempotency means that performing the same operation multiple times produces the same result as performing it once. This property is critical in automation and distributed systems where network failures or retries may cause a request to be sent more than once. APIs, payment processing, and deployment scripts should be designed to be idempotent so that retries are safe and don't create duplicate side effects.

Infinite scroll is a UX pattern where new content loads automatically as the user scrolls toward the bottom of the page, eliminating traditional pagination. It's commonly used in social media feeds and content discovery interfaces. While it increases engagement and feels seamless, it can hurt performance without virtualization and makes it difficult for users to reach footer content or bookmark specific positions.

Infrastructure as Code (IaC) is the practice of managing and provisioning servers, networks, and cloud resources through machine-readable configuration files rather than manual processes. It enables version control, code review, and automated testing of infrastructure changes just like application code. Tools like Terraform, Pulumi, and AWS CloudFormation are popular IaC solutions that make environments reproducible and consistent.

Internationalization (i18n) is the process of designing software so it can be adapted to different languages, regions, and cultures without code changes. This involves externalizing strings, supporting right-to-left (RTL) layouts, handling date/number/currency formatting, and accommodating text expansion. Libraries like react-intl, next-intl, and i18next provide the infrastructure for managing translations and locale-aware formatting in JavaScript applications.