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Plans to support Next.js 13 - /app directory

See original GitHub issue

The problem

Next JS just release their v13 publicly. As seen in their docs, emotion has not yet added support.

Is there any plan to add support in the near future?

Thanks.

Issue Analytics

State:
Created a year ago
Reactions:154
Comments:41 (10 by maintainers)

Top GitHub Comments

43reactions

emmatowncommented, Oct 27, 2022

We may want to add an explicit API for this but this works today:

// app/emotion.tsx
"use client";
import { CacheProvider } from "@emotion/react";
import createCache from "@emotion/cache";
import { useServerInsertedHTML } from "next/navigation";
import { useState } from "react";

export default function RootStyleRegistry({
  children,
}: {
  children: JSX.Element;
}) {
  const [cache] = useState(() => {
    const cache = createCache({ key: "css" });
    cache.compat = true;
    return cache;
  });

  useServerInsertedHTML(() => {
    return (
      <style
        data-emotion={`${cache.key} ${Object.keys(cache.inserted).join(" ")}`}
        dangerouslySetInnerHTML={{
          __html: Object.values(cache.inserted).join(" "),
        }}
      />
    );
  });

  return <CacheProvider value={cache}>{children}</CacheProvider>;
}

// app/layout.tsx
import RootStyleRegistry from "./emotion";

export default function RootLayout({ children }: { children: JSX.Element }) {
  return (
    <html>
      <head></head>
      <body>
        <RootStyleRegistry>{children}</RootStyleRegistry>
      </body>
    </html>
  );
}

// app/page.tsx
/** @jsxImportSource @emotion/react */
"use client";

export default function Page() {
  return <div css={{ color: "green" }}>something</div>;
}

23reactions

Andaristcommented, Nov 18, 2022

After talking with the Next.js team and helping them recognize the problem with useServerInsertedHTML and Suspense that issue has been fixed in https://github.com/vercel/next.js/pull/42293

With that fix Emotion roughly works in the /app if you do this:

"use client";
import { CacheProvider } from "@emotion/react";
import createCache from "@emotion/cache";
import { useServerInsertedHTML } from "next/navigation";
import { useState } from "react";

export default function RootStyleRegistry({
  children,
}: {
  children: JSX.Element;
}) {
  const [{ cache, flush }] = useState(() => {
    const cache = createCache({ key: "my" });
    cache.compat = true;
    const prevInsert = cache.insert;
    let inserted: string[] = [];
    cache.insert = (...args) => {
      const serialized = args[1];
      if (cache.inserted[serialized.name] === undefined) {
        inserted.push(serialized.name);
      }
      return prevInsert(...args);
    };
    const flush = () => {
      const prevInserted = inserted;
      inserted = [];
      return prevInserted;
    };
    return { cache, flush };
  });

  useServerInsertedHTML(() => {
    const names = flush();
    if (names.length === 0) return null;
    let styles = "";
    for (const name of names) {
      styles += cache.inserted[name];
    }
    return (
      <style
        data-emotion={`${cache.key} ${names.join(" ")}`}
        dangerouslySetInnerHTML={{
          __html: styles,
        }}
      />
    );
  });

  return <CacheProvider value={cache}>{children}</CacheProvider>;
}

(kudos to the @emmatown for providing this implementation)

We need to figure out the exact APIs for handling this within Emotion but conceptually the thing would end up being very similar - you just won’t have to override cache.insert in the future and we’ll provide this new kind of the flush in Emotion itself.

Note that you should only use Emotion with the so-called client components (we might add "use client"; directive to our files to make this obvious). They can render on the server just fine - for the initial SSRed/streamed HTML but server “refetches” won’t render them on the server, they might be rendered on the client when the “refetch” response comes back. This is not Emotion’s limitation - it’s a limitation for all CSS-in-JS libs like Emotion (including Styled Components, styled-jsx and more)