Repository navigation
Conversation
|
The latest updates on your projects. Learn more about Vercel for GitHub.
|
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #9212 +/- ##
==========================================
+ Coverage 86.07% 86.15% +0.08%
==========================================
Files 86 86
Lines 6060 6075 +15
Branches 359 360 +1
==========================================
+ Hits 5216 5234 +18
+ Misses 840 837 -3
Partials 4 4 ☔ View full report in Codecov by Harness. |
Contributor
There was a problem hiding this comment.
🟡 Changes recommended
The supplied-highlighter path needs an automated regression test proving bundled grammars remain unloaded.
1 open finding
What changed in this PR
Defers loading bundled Shiki grammars when callers provide their own highlighter, reducing import overhead for consumers such as nodejs/doc-kit.
Changes:
- Dynamically imports the default highlighter only when needed.
- Adds a patch changeset.
| File | Description |
|---|---|
packages/rehype-shiki/src/plugin.mjs |
Lazily loads the grammar-heavy default highlighter. |
.changeset/lazy-rehype-shiki-highlighter.md |
Records the patch release. |
🧠 Review effort: Balanced
💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.
ovflowd
added a commit
to nodejs/doc-kit
that referenced
this pull request
Oct 10, 2026
The Shiki plugin registered every bundled language (~250 grammars) in each thread that highlighted code, which cost ~2s and ~100MB per thread and made every highlight several times slower, as each code block was matched against grammars it never uses. Importing it also imported all of them, through `@node-core/rehype-shiki`'s `LANGS` and its plugin, on every thread loading `jsx-ast`, the main thread included. The highlighter now registers a bundled language the first time code in it is highlighted, along with the bundled languages a configured one embeds, and lists the bundled ones from their metadata alone, without importing `LANGS`. The themes are given to Shiki by name, which it keeps parsed instead of parsing them for every highlight. Importing `@node-core/rehype-shiki`'s plugin still imports every grammar until nodejs/nodejs.org#9212 is released. The grammars now come from doc-kit's own `shiki` dependency (4.4.3) rather than the copy `@node-core/rehype-shiki` pins (4.3.1). Its C++ grammar highlights types and template arguments differently, which shows on the Node.js docs' C++ examples. Assisted-by: Claude Opus 5.5 <noreply@anthropic.com>
4 tasks done
avivkeller
approved these changes
Oct 10, 2026
Contributor
📦 Build Size ComparisonSummary
|
ovflowd
added a commit
to nodejs/doc-kit
that referenced
this pull request
Oct 10, 2026
The Shiki plugin registered every bundled language (~250 grammars) in each thread that highlighted code, which cost ~2s and ~100MB per thread and made every highlight several times slower, as each code block was matched against grammars it never uses. Importing it also imported all of them, through `@node-core/rehype-shiki`'s `LANGS` and its plugin, on every thread loading `jsx-ast`, the main thread included. The highlighter now registers a bundled language the first time code in it is highlighted, along with the bundled languages a configured one embeds, and lists the bundled ones from their metadata alone, without importing `LANGS`. The themes are given to Shiki by name, which it keeps parsed instead of parsing them for every highlight. Importing `@node-core/rehype-shiki`'s plugin still imports every grammar until nodejs/nodejs.org#9212 is released. The grammars now come from doc-kit's own `shiki` dependency (4.4.3) rather than the copy `@node-core/rehype-shiki` pins (4.3.1). Its C++ grammar highlights types and template arguments differently, which shows on the Node.js docs' C++ examples. Assisted-by: Claude Opus 5.5 <noreply@anthropic.com>
The plugin imported `index.mjs` statically, and that module imports every grammar Shiki bundles (`LANGS`) as soon as it's loaded, so a caller passing its own highlighter still paid for all of them: 260 grammar modules on each thread that loads the plugin. It's now imported only when the plugin has to create a highlighter itself. This lets doc-kit, which highlights with a highlighter that loads grammars on demand, use the plugin rather than a copy of it. Assisted-by: Claude Opus 5.5 <noreply@anthropic.com>
ovflowd
force-pushed
the
fix/rehype-shiki-lazy-highlighter
branch
from
October 10, 2026 18:00
36ac193 to
e1c50ce
Compare
This branch was successfully deployed
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Description
This PR makes
@node-core/rehype-shiki's plugin importindex.mjsonly when it has to create a highlighter itself.plugin.mjsimportedindex.mjsstatically, and that module imports every grammar Shiki bundles (LANGS) as soon as it's loaded. So a caller passing its ownhighlighterstill paid for all of them: importing the plugin loaded 260 grammar modules on every thread that used it. It's now a dynamic import, inside the branch that creates the default highlighter, and a patch changeset releases it.Validation
lint:jsand Prettier.plugin.mjsloads 260 grammar modules before this change and none after it, counted with a moduleloadhook.Related Issues
Refs: nodejs/doc-kit#1156, which highlights with its own highlighter that loads grammars on demand, and can then use this plugin instead of a copy of it.
Check List
pnpm formatto ensure the code follows the style guide.pnpm testto check if all tests are passing.pnpm buildto check if the website builds without errors.