React Hooks

A task runner is a tool that automates repetitive development tasks like compiling code, running tests, minifying assets, and restarting servers. Early web task runners like Grunt and Gulp defined workflows as JavaScript code, while modern approaches use npm scripts, Turborepo, or Nx for monorepo-aware task orchestration. Task runners form the foundation of local development automation, ensuring every team member runs tasks consistently.

Storybook is an open-source tool for building and testing UI components in isolation, outside of your main application. Developers define "stories" — different states and variations of a component — which are rendered in a dedicated browser-based workshop. It supports React, Vue, Angular, and other frameworks, making it invaluable for component documentation, visual regression testing, and collaboration between designers and developers.

A cron job is a time-based task scheduler originating from Unix systems that runs commands or scripts at specified intervals. The schedule is defined using a cron expression with five fields representing minute, hour, day, month, and weekday. Cron jobs are fundamental for automations like database backups, log rotation, report generation, and periodic data synchronization.

Container Queries allow CSS styles to respond to the size of a parent container rather than the browser viewport, solving a long-standing limitation of media queries. By marking an element as a containment context with `container-type`, its children can use `@container` rules to adapt their layout based on the container's dimensions. This makes truly reusable components possible — a card component can rearrange itself whether it's in a sidebar or a full-width section.

A controlled component is a form element in React whose value is driven by React state rather than the DOM's own internal state. The component's value is set through a `value` prop and updated via an `onChange` handler, giving React full control over the form data. This pattern enables validation on every keystroke, conditional disabling of submit buttons, and enforcing input formats, making it the recommended approach for most form handling in React applications.

A canary release is a deployment strategy where a new version is gradually rolled out to a small subset of users before reaching the full audience. Automated monitoring compares error rates, latency, and key metrics between the canary and the stable version. If the canary performs well, traffic is incrementally shifted; if anomalies are detected, the release is automatically rolled back, minimizing the blast radius of potential issues.