org.webjars.npm:rehackt

Rehackt

This package is fairly advanced and is only intended for library developers that want to maintain high interop with Next.js server actions.

Rehackt invisibly wraps react so that you're able to use shared imports with react in server-side Next.js code without throwing an error to your users.

Explainer

Assume you have the following code in a Next.js codebase:

"use client"

import { useFormState } from "react-dom"
import someAction from "./action";

export const ClientComp = () => {
  const [data, action] = useFormState(someAction, "Hello client");

  return <form action={action}>
    <p>{data}</p>
    <button type={"submit"}>Update data</button>
  </form>
}

"use server"
// action.ts

import {data} from "./shared-code";

export default async function someAction() {
  return "Hello " + data.name;
}

// shared-code.ts
import {useState} from "react";

export const data = {
  useForm: <T>(val: T) => {
      useState(val)
  },
  name: "server"
}

While you're not intending to use data.useForm in your action.ts server-only file, you'll still receive the following error from Next.js' build process when trying to use this code:

./src/app/shared-code.ts
ReactServerComponentsError:

You're importing a component that needs useState. It only works in a Client Component but none of its parents are marked with "use client", so they're Server Components by default.
Learn more: https://nextjs.org/docs/getting-started/react-essentials

   ╭─[/src/app/shared-code.ts:1:1]
 1 │ import {useState} from "react";
   ·         ────────
 2 │ 
 3 │ export const data = {
 3 │   useForm: <T>(val: T) => {
   ╰────

Maybe one of these should be marked as a client entry with "use client":
./src/app/shared-code.ts
./src/app/action.ts

This is because Next.js statically analyzes usage of useState to ensure it's not being utilized in server-only code.

By replacing the import from react to rehackt:

// shared-code.ts
import {useState} from "rehackt";

export const data = {
  useForm: <T>(val: T) => {
      useState(val)
  },
  name: "server"
}

You'll no longer see this error.

Keep in mind, this does not enable usage of useState in server-only code, this just removes the error described above.

Further Reading

The following is a list of reading resources that pertain to this package:

• My take on the current React & Server Components controversy - Lenz Weber-Tronic

• apollographql/apollo-client#10974

• TanStack/form#480