migrate-mdc-to-comark

Development

Migrate a Nuxt project from @nuxtjs/mdc to Comark. Covers package changes, parse/render API mapping, AST format, Nuxt module config, components, slots, plugins, and Nuxt UI integration.

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Migrate from @nuxtjs/mdc to Comark

@nuxtjs/mdc was Nuxt-only. Comark is its successor: the markdown syntax is fully compatible, your .md files need no changes. What changes is the JavaScript API.

The migration has two parts: Core Package (programmatic API) and Nuxt Module (components, slots, config).

Quick Overview

Package: @nuxtjs/mdc → comark (core only) or @comark/nuxt (Nuxt module)
Parse: parseMarkdown() → parse() · factory: createParse() (sync, no await)
Render: stringifyMarkdown() → renderMarkdown() from comark/render
AST: object tree → compact tuples ['tag', props, ...children]
Result: result.body / result.data → tree.nodes / tree.frontmatter
Renderer: <MDCRenderer :body :data> → <ComarkRenderer :tree>
All-in-one: <MDC :value> → <Comark :markdown>
Slots: <MDCSlot /> → native <slot />
Plugins: global nuxt.config → per-component defineComarkComponent({ plugins })
Markdown files: no changes needed

Core Package

API Mapping

`@nuxtjs/mdc`	`comark`
`parseMarkdown(md, opts)`	`parse(md, opts)` from `comark`
`createMarkdownParser(opts)` (async)	`createParse(opts)` (sync, no await)
`stringifyMarkdown(body, data)`	`renderMarkdown(tree)` from `comark/render`
`result.body` (`MDCRoot`)	`tree.nodes` (`ComarkNode[]`)
`result.data`	`tree.frontmatter`
`result.data.title`	`tree.frontmatter.title`
`result.toc`	`tree.meta.toc` (requires `toc` plugin)
`result.excerpt`	`tree.meta.summary` (requires `summary` plugin)

AST Format

`@nuxtjs/mdc`	`comark`
`{ type: 'root', children: MDCNode[] }`	`{ nodes: ComarkNode[], frontmatter: {}, meta: {} }`
`{ type: 'element', tag: 'p', props: {}, children: [] }`	`['p', {}, ...children]`
`{ type: 'text', value: 'hello' }`	`'hello'` (plain string)

Parse Options

// Before: MDCParseOptions
{
  remark: { plugins: { /* record */ } },
  rehype: { options: {...}, plugins: { /* record */ } },
  highlight: { theme: '...', langs: [...] } | false,
  toc: { depth: 3, searchDepth: 2 } | false,
}

// After: ParseOptions
{
  plugins: ComarkPlugin[],   // ordered array, not a record
  autoUnwrap: true,          // removes <p> from single-paragraph containers
  autoClose: true,           // completes incomplete syntax (useful for streaming)
  html: true,                // parse embedded HTML tags
}

Plugins

The unified/remark/rehype pipeline is replaced by Comark's own lighter plugin interface.

Feature	Before	After
Syntax highlighting	`rehypeHighlight` via `createMarkdownParser`	`highlight()` from `comark/plugins/highlight`
Table of Contents	`parseMarkdown(md, { toc: { depth: 3 } })`	`toc({ depth: 3 })` plugin
Excerpt / Summary	`result.excerpt` (built-in)	`summary()` plugin → `tree.meta.summary`
Emoji	`remark-emoji` (enabled by default)	`emoji()` plugin (opt-in)

Available plugins: comark/plugins/toc, comark/plugins/highlight, comark/plugins/emoji, comark/plugins/task-list, comark/plugins/summary, comark/plugins/security, comark/plugins/alert, comark/plugins/math, comark/plugins/mermaid, comark/plugins/punctuation

Nuxt Module

Configuration

// Before
export default defineNuxtConfig({
  modules: ['@nuxtjs/mdc'],
  mdc: { highlight: { ... }, remarkPlugins: { ... } },
})

// After
export default defineNuxtConfig({
  modules: ['@comark/nuxt'],
  // No plugin config here (plugins are defined per-component)
})

@comark/nuxt auto-imports: Comark, ComarkRenderer, defineComarkComponent, defineComarkRendererComponent.

Components

`@nuxtjs/mdc`	`@comark/nuxt`
`<MDCRenderer :body :data :components>`	`<ComarkRenderer :tree :components>`
`<MDC :value :parser-options>`	`<Comark :markdown :options>` or `<Comark>{{ md }}</Comark>`
`<MDCSlot />`	`<slot />`
`<MDCSlot unwrap="p" />`	`<slot unwrap="p" />`
`<slot mdc-unwrap="p" />`	`<slot unwrap="p" />`

For a pre-parsed tree, use <ComarkRenderer> directly instead of <Comark>.

`<ComarkRenderer>` props changes

MDC `<MDCRenderer>`	Comark `<ComarkRenderer>`	Notes
`body` (`MDCRoot`)	`tree` (`ComarkTree`)	Different AST shape
`data`	—	Frontmatter is in `tree.frontmatter`
`tag`	—	Wrapper is always `<div class="comark-content">`
`prose`	—	`Prose*` resolution is automatic
`unwrap`	—	Use `autoUnwrap` in parse options
`components`	`components`	Same purpose
—	`componentsManifest`	New: dynamic async component resolver
—	`streaming`	New: streaming mode
—	`caret`	New: animated caret for streaming

Summary rendering

<!-- Before -->
<MDCRenderer :body="result.excerpt ?? result.body" :data="result.data" />

<!-- After -->
<Comark summary>{{ markdown }}</Comark>

`defineComarkComponent`

Replaces global mdc: { ... } config. Define reusable components with their own plugins and component mappings:

import { defineComarkComponent } from '@comark/vue'
import highlight from 'comark/plugins/highlight'
import toc from 'comark/plugins/toc'

export const ArticleComark = defineComarkComponent({
  name: 'ArticleComark',
  plugins: [highlight({ themes: { light: githubLight, dark: githubDark } }), toc()],
  components: { alert: CustomAlert },
})

Slots

<MDCSlot /> → native <slot />. Named slots work the same (#slotName in markdown, <slot name="slotName"> in component). The unwrap attribute (<slot unwrap="p">) strips wrapper tags from children.

Prose Components

Same Prose*.vue naming convention in components/prose/. Resolution changed from kebab-case (prose-p) to PascalCase (ProseP) internally. No file changes needed.

Nuxt UI Integration

When using Nuxt UI, @comark/nuxt registers Nuxt UI prose components automatically. Shorthand callout components are available:

::note    (informational)
::tip     (helpful suggestion)
::warning (something to watch out for)
::caution (critical warning)

These are only available with Nuxt UI. Without it, use ::callout{icon="..." color="..."}.

Common Pitfalls

createParse is sync: no await needed (unlike createMarkdownParser)
Attribute naming: Comark uses attrs.lang, not attrs.language
Frontmatter: stored in tree.frontmatter, not passed separately
renderMarkdown includes frontmatter: reads tree.frontmatter automatically
No unified pipeline: mdc.config.ts hooks (pre, remark, rehype, post) have no equivalent, use ComarkPlugin interface instead
Emoji is opt-in: not enabled by default like in MDC's remark-emoji

Component Syntax

The MDC block and inline component syntax is identical, so no changes are needed in .md files.

Unsupported Features

Binding syntax ({{ variable }}): not supported, rendered as plain text
Props binding / data passing: no equivalent for parseMarkdown(md, { data: { ... } })