[Beta] Fully SSR CodeBlock

[gaearon]

Our CodeBlock uses the same mechanism for highlighting as regular Sandpack instance. This isn't great for two reasons:

• We have to run the highlighting parser during hydration.
• The CodeMirror "decorations" like line and inline highlight only attach after hydration, causing a visible jump.

This rewrites the logic to be 100% inline without dependency on Sandpack. Instead, we roughly do what the Sandpack implementation does under the hood. We also remove a bunch of logic we don't need (like actually initializing CodeMirror). I've reimplemented the logic for placing highlights and decorations by hand.

Ideally, this would run only on the server. If we had Server Components, this would be one, but since we don't yet, I'll send a follow-up PR to do some ad-hoc preprocessing so this never has to run on the client.

[github-actions]

Size Changes

📦 Next.js Bundle Analysis

This analysis was generated by the next.js bundle analysis action 🤖

⚠️ Global Bundle Size Increased

Page	Size (compressed)
global	87.77 KB (🟡 +20 B)

Details

The global bundle is the javascript bundle that loads alongside every page. It is in its own category because its impact is much higher - an increase to its size means that every page on your website loads slower, and a decrease means every page loads faster.

Any third party scripts you have added directly to your app using the <script> tag are not accounted for in this analysis

If you want further insight into what is behind the changes, give @next/bundle-analyzer a try!

Three Pages Changed Size

The following pages changed size from the code in this PR compared to its base branch:

Page	Size (compressed)	First Load
/404	42.8 KB (🟡 +2 B)	130.57 KB
/500	42.78 KB (🟡 +2 B)	130.55 KB
/[[...markdownPath]]	42.86 KB (🟡 +2 B)	130.63 KB

Details

Only the gzipped size is provided here based on an expert tip.

First Load is the size of the global bundle plus the bundle for the individual page. If a user were to show up to your website and land on a given page, the first load size represents the amount of javascript that user would need to download. If next/link is used, subsequent page loads would only need to download that page's bundle (the number in the "Size" column), since the global bundle has already been downloaded.

Any third party scripts you have added directly to your app using the <script> tag are not accounted for in this analysis

Next to the size is how much the size has increased or decreased compared with the base branch of this PR. If this percentage has increased by 10% or more, there will be a red status indicator applied, indicating that special attention should be given to this.

[danilowoz]

Interesting, I think we can implement this on Sandpack itself because the CodeBlock component on Sandpack is also static and read-only. The only dependency from CodeMirror on this component was the decorator, but you just decoupled the logic, which seems a very good plan.

Hope you're fine if I use this implementation on Sandpack :D codesandbox/sandpack#577

[gaearon]

sounds great!