When working on projects that target both web and mobile, developers often face duplicated effort in building UI components. A shared component system not only reduces code duplication but also ensures a consistent look and feel across platforms. This guide walks through the essential steps to design, implement, and maintain a unified component library for React Web and React Native. Why Share Components? - Consistency: Users encounter the same visual language whether they open the app in a browser or on a phone. - Code Reuse: Write once, use everywhere. This saves time and minimizes bugs that arise from divergent implementations. - Team Efficiency: Designers and developers can work from a single source of truth, simplifying handoffs and updates. Key Strategies 1. Define Design Tokens First - Create a small set of variables for colors, spacing, typography, and shadows. - Store them in a shared package (e.g., `../design-tokens`) that both web and native projects can import. 2. Build Component Abstractions - Use a common interface (often TypeScript definitions) to describe props for each component. - Export the same component name from separate packages (e.g., `@myui/button-web` and `@myui/button-native`) while keeping the implementation platform‑specific. 3. Leverage Custom Hooks for Platform‑Specific Logic - For example, a `useKeyboardHeight` hook can be implemented differently for web (using `resizeObserver`) and native (using `Keyboard` events) but exported from a single library. 4. Adopt a Monorepo or Lerna Setup - This makes it easier to version, publish, and link packages across projects. Implementation Steps - Set up a separate repository for the component library (e.g., `@myui/core`). - Write design tokens in a JSON file and export them as SCSS variables for web and plain JS objects for native. - Create a component skeleton in a shared folder, then duplicate it into `src/web` and `src/native` with platform‑specific adapters (e.g., `Pressable` for web becomes `button` for native). - Use a build tool like Storybook to showcase components and ensure they render correctly on both platforms. - Add unit tests that run in a Node environment for web and Jest with React Native for mobile. Best Practices - Keep component APIs simple; avoid over‑engineering with too many optional props. - Document each component with usage examples and platform‑specific notes. - Run a linting and formatting check across all packages to maintain code style. - Periodically audit the library to remove unused components and refactor duplicated logic. Conclusion A shared UI component system streamlines development, improves consistency, and accelerates delivery for React Web and React Native applications. By focusing on design tokens, clear abstractions, and reusable hooks, teams can build a robust library that scales with their product’s growth.