Why is this lib needed in Nextjs (app router)? #155

PeturSteinn · 2024-10-10T21:15:07Z

PeturSteinn
Oct 10, 2024

Just curious for why this library is needed at all with the app router in Nextjs.
I just don't know why I would need the script tag at all? Like why is it not good enough to populate a context provider via root layout, where I can just stick my prefered environment variables in the value and then consume that provider wherever I want?

Here's a minimal setup that I have in my head:

import env from '@/env';
export default function RootLayout({ children }: { children: React.ReactNode }) {
  // This object can be created dynamically with some startsWith condition that I could have for my env vars that i would want to expose to the client.
  const runtimeEnv = {
    MY_VAR: env.MY_VAR,
    FOO: env.FOO,
  }

  return (
    <html lang="en">
      <body>
        {/* Provide the env values from the root layout */}
        <RuntimeEnvProvider env={runtimeEnv}>
          {children}
        </RuntimeEnvProvider>
      </body>
    </html>
  );
}

Then <RuntimeEnvProvider /> is just a regular old context provider

// context/RuntimeEnvContext.tsx
"use client";
import React, { createContext, useContext, ReactNode } from 'react';

// This could be stored elsewhere or just be a dynamic type somehow
type RuntimeEnvContextType = {
  MY_VAR: string;
  FOO: string;
};

const RuntimeEnvContext = createContext<RuntimeEnvContextType | undefined>(undefined);

export const RuntimeEnvProvider = ({ children, env }: { children: ReactNode; env: RuntimeEnvContextType }) => {
  return (
    <RuntimeEnvContext.Provider value={env}>
      {children}
    </RuntimeEnvContext.Provider>
  );
};

export const useRuntimeEnv = (): RuntimeEnvContextType => {
  const context = useContext(RuntimeEnvContext);
  if (!context) {
    throw new Error('useRuntimeEnv must be used within a RuntimeEnvProvider');
  }
  return context;
};

Then consuming it on the client would be easy like this....

// app/_components/foo.tsx
"use client"
import { useRuntimeEnv } from '@/context/RuntimeEnvContext';

export default function Foo() {
  const { MY_VAR, FOO } = useRuntimeEnv();

  return (
    <div className="container">
      <h1>Welcome to {MY_VAR}</h1>
      <p>FOO is: {FOO}</p>
    </div>
  );
}

I've got to be missing something, and I'm sorry if I am but I just have no idea why the script thing is needed at all.

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Why is this lib needed in Nextjs (app router)? #155

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Why is this lib needed in Nextjs (app router)? #155

PeturSteinn Oct 10, 2024

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PeturSteinn
Oct 10, 2024