Client and Server Components

INFO

From the React documentation: "A component usage is considered a Client Component if it is defined in module with use client directive or when it is a transitive dependency of a module that contains a use client directive. Otherwise, it is a Server Component."

Only the App Component must be a Server Component. Other components (and modules) can run on the server, the client, or both. For example, the following Counter component is a Client Component:

src/Counter.tsx

tsx

"use client";

import React, { useState } from "react";

export default function Counter() {
  const [count, setCount] = useState(0);

  return (
    <button onClick={() => setCount((prev) => prev + 1)}>
      Counter is: {count}
    </button>
  );
}

And the App Component is a Server Component.

src/index.tsx

tsx

import type { AppProps } from "react-just";
import Counter from "./Counter";

export default async function App(props: AppProps) {
  return (
    <html>
      <body>
        <h1>Hello from the server</h1>
        <Counter />
      </body>
    </html>
  );
}

Client and Server Components ​

Client and Server Components