React interfaces are built from components: reusable pieces that receive data, render content and respond to user actions. A well-structured component tree can make a screen easier to understand, but breaking every line into a separate component is not the goal. Choose boundaries that keep each component focused.
Props pass information; state changes
Props are inputs supplied by a parent component. State represents information that changes over time, such as a selected filter or a form value. Keep state close to the components that need it and avoid storing values that can be derived from other state. This reduces accidental inconsistencies.
Render lists and conditions
When rendering a collection, provide a stable key so React can associate each item with its rendered output. Conditional rendering can show a loading message, an empty-state explanation or an error response. These are distinct situations: a failed request should not be disguised as a successful empty list.
Build forms with users in mind
Use labels connected to inputs, clear instructions and useful error text. Controlled inputs keep values synchronized with component state. Client-side checks can make a form easier to use, but they do not protect the server; every request must be validated again in the backend. Provide keyboard support and visible focus styles.
Handle API states
For each request, decide how the interface behaves while waiting, when data arrives, when there is no data and when something fails. Consider what happens if a user changes a filter before an earlier request finishes. A small service function or custom hook can keep request logic out of large components.
Practice by building a catalog
- Create a page shell, search filter, item list and item-card components.
- Pass item data through props and keep the search query in state.
- Render loading, empty, error and success states.
- Add a labeled form to create a mock item and show validation feedback.
- Test the flow with keyboard navigation and a failed API response.
Use fictional records and avoid placing secrets in browser code. See the MERN Full Stack Developer Course and the React components and forms topic guide.