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React

Examples:

@lumis-sh/react follows the same formatter-first API as the rest of Lumis, but splits client and server helpers.

Install​

npm install @lumis-sh/react @lumis-sh/lumis @lumis-sh/themes react

Client component​

Use CodeBlock when you want a drop-in React component.

Simple​

import {CodeBlock} from '@lumis-sh/react'

import {htmlInline} from '@lumis-sh/lumis/formatters'

import githubLight from '@lumis-sh/themes/github_light'



const codeString = `export function Hello() {

  return <h1>Hello</h1>

}`



export function Example() {

  return (

    <CodeBlock formatter={htmlInline({language: 'tsx', theme: githubLight})}>

      {codeString}

    </CodeBlock>

  )

}

Reuse one highlighter​

import {CodeBlock} from '@lumis-sh/react'

import {createHighlighter} from '@lumis-sh/lumis'

import {bundledLanguages} from '@lumis-sh/lumis/bundles/web'

import {htmlInline} from '@lumis-sh/lumis/formatters'

import githubLight from '@lumis-sh/themes/github_light'



const highlighter = createHighlighter({languages: [bundledLanguages]})



const codeString = `export function Hello() {

  return <h1>Hello</h1>

}`



export function Example() {

  return (

    <CodeBlock

      highlighter={highlighter}

      formatter={htmlInline({language: bundledLanguages.tsx, theme: githubLight})}

    >

      {codeString}

    </CodeBlock>

  )

}

If you do not pass highlighter, CodeBlock uses a shared internal highlighter. Passing your own highlighter is the better choice when you want to preload bundles or reuse one instance across many blocks.

Hook​

Use useLumis() when you want to control the loading UI yourself.

import {useLumis} from '@lumis-sh/react'

import {createHighlighter} from '@lumis-sh/lumis'

import {bundledLanguages} from '@lumis-sh/lumis/bundles/web'

import {htmlInline} from '@lumis-sh/lumis/formatters'

import githubLight from '@lumis-sh/themes/github_light'



const highlighter = createHighlighter({languages: [bundledLanguages]})



export function Example() {

  const {content, isLoading} = useLumis({

    children: 'export const answer = 42',

    formatter: htmlInline({language: 'typescript', theme: githubLight}),

    highlighter,

  })



  if (isLoading) return <p>Loading syntax highlighter...</p>

  return <>{content}</>

}

Server rendering​

Use renderCodeBlock() from the server subpath when you need highlighted output on the server.

This is a good fit for React Server Components and Next.js App Router pages.

import {renderCodeBlock} from '@lumis-sh/react/server'

import {bundledLanguages} from '@lumis-sh/lumis/bundles/web'

import {htmlInline} from '@lumis-sh/lumis/formatters'

import githubLight from '@lumis-sh/themes/github_light'



const codeString = `export function Hello() {

  return <h1>Hello</h1>

}`



export async function Article() {

  const block = await renderCodeBlock({

    children: codeString,

    formatter: htmlInline({language: bundledLanguages.tsx, theme: githubLight}),

  })



  return <article>{block}</article>

}

Reusing one highlighter​

Create one Highlighter and pass it into CodeBlock or useLumis():

import {createHighlighter} from '@lumis-sh/lumis'

import {bundledLanguages} from '@lumis-sh/lumis/bundles/web'

import {CodeBlock} from '@lumis-sh/react'

import {htmlInline} from '@lumis-sh/lumis/formatters'

import githubLight from '@lumis-sh/themes/github_light'



const codeString = `export const answer = 42`



const highlighter = await createHighlighter({languages: [bundledLanguages]})



export function Example() {

  return (

    <CodeBlock

      highlighter={highlighter}

      formatter={htmlInline({language: 'tsx', theme: githubLight})}

    >

      {codeString}

    </CodeBlock>

  )

}

This is the best option when you want to preload a bundle and render many code blocks on one page.

Behavior​

  • formatter is the single source of truth for the language
  • CodeBlock and useLumis() are client exports from @lumis-sh/react
  • renderCodeBlock() is a server export from @lumis-sh/react/server
  • the React helpers call highlighter.loadLanguage(formatter.language) before highlighting
  • when the language is already loaded, Lumis reuses the cached result
  • for true server-rendered highlighting, prefer renderCodeBlock()
  • CodeBlock and useLumis() re-highlight when children, formatter, or highlighter changes