devvbankx@devs_lyfe
I’m researching RSCs. ‘use server’ indicates server code that’s allowed in client side.
the 'use server' directive marks server-side executable code (specifically Server Actions or Server Functions) that can be referenced and invoked from client-side code, without shipping the actual function body to the client.
Server Components (the main RSC feature) are the default — no directive needed. They run exclusively on the server; their code never reaches the client bundle. The client receives only the rendered output (via the React Flight protocol — a streamed, serialized tree of JSON-like chunks representing elements, not code).
• 'use server' is not for marking Server Components. It’s specifically for Server Actions (async functions that perform mutations or other server-side work).
• These actions are allowed to be called from Client Components (marked with 'use client'), but the function implementation stays server-only.
So more precisely: 'use server' indicates server-only functions that are callable (via RPC-like invocation) from client code.
React/Next.js does not include the function’s source code in the client JS bundle.
Instead:
• During build (or dynamically), the framework replaces the imported function with a lightweight reference / proxy object.
• This reference is typically a serialized identifier — often a string like a module ID + export name hash, or an encoded reference in the RSC payload format.
• When invoked from the client:
1. React serializes arguments (must be JSON-serializable: primitives, objects, FormData, etc.; no functions, Dates need special handling, etc.).
2. Sends a POST request (usually to a special endpoint like /_next/actions/... in Next.js) with the reference ID + args.
3. Server receives it, looks up the real function by the ID, executes it, serializes the return value, and sends it back.
4. Client receives and resolves the promise.
Just beginning. But I’m on to something
