Programming (Python, JavaScript, C#) · IACT Training Blog
React remains the most widely used library for building user interfaces, and React 19 brings meaningful quality-of-life improvements for beginners and teams alike. If you can write basic JavaScript, you can be productive in React in an afternoon. This crash course covers the core mental model and the React 19 additions worth learning early.
Components, JSX and props
Everything in React is a component, a JavaScript function that returns markup written in JSX. JSX lets you describe UI with HTML-like syntax inside JavaScript, so return <h1>Hello</h1> renders a heading. Components compose: a page is built from smaller, reusable pieces.
Props are how data flows into a component, passed in like HTML attributes. A <Welcome name="Aoife" /> component receives props.name and renders it. Props are read-only, which keeps data flow predictable and one-directional, the single most important idea to internalise early.
State and hooks
When a component needs to remember something that changes, you use state. The useState hook returns the current value and a function to update it: const [count, setCount] = useState(0). Calling setCount re-renders the component with the new value. The useEffect hook runs side effects such as fetching data after render.
Hooks are just functions that let function components use React features. Learn useState and useEffect first; the rest follow naturally once the pattern clicks.
What is new in React 19
- Actions: built-in handling of pending states, errors and form submissions, reducing boilerplate.
- The
useAPI for reading promises and context more ergonomically. - Improved form handling with
useActionStateanduseFormStatus. - Better support for document metadata and async rendering.
For beginners, these mean less manual wiring for common tasks like submitting a form and showing a loading spinner, work that previously required several pieces of state.
A sensible learning path
Start by building something small and real, a to-do list or a weather lookup. Master components, props and useState before reaching for routing, state libraries or a framework like Next.js. Use the official React documentation as your reference and a structured course or crash-course video to give the concepts order. Practice beats passive watching every time.
Train with IACT
IACT teaches web development and programming from first principles, including JavaScript and modern front-end frameworks. Go from beginner to building real apps with expert guidance.