A Look at React 19 New Features

A Look at React 19 New Features

Published on: 2026-07-25
tech

Introduction

React 19 is finally stable, bringing Actions, useOptimistic, useFormStatus, and a series of new APIs. These updates fundamentally change how we write async interactions.

Actions

Actions are React 19's most important concept. Simply put, you can pass an async function to <form action={...}>, and React will automatically manage pending state, error handling, and optimistic updates.

function UpdateName() {
  const [name, setName] = useState("");
  const [error, setError] = useState(null);
  const [isPending, startTransition] = useTransition();

  const handleSubmit = () => {
    startTransition(async () => {
      const error = await updateName(name);
      if (error) {
        setError(error);
        return;
      }
      redirect("/path");
    });
  };

  return (
    <div>
      <input value={name} onChange={(e) => setName(e.target.value)} />
      <button onClick={handleSubmit} disabled={isPending}>
        Update
      </button>
      {error && <p>{error}</p>}
    </div>
  );
}

useOptimistic

useOptimistic lets you optimistically update the UI before the request completes, automatically rolling back on failure. Useful for high-frequency interactions like likes and comments.

Summary

React 19's core idea: sink async interaction state management into the framework layer. Developers only care about business logic; pending/error/optimistic are handled by React.

← Back to home