Code Block

Installation

$ pnpm dlx shadcn@latest add @byphongphan/code-block

Anatomy

CodeBlock├── CodeBlockHeader│   ├── CodeBlockTitle│   ├── CodeBlockLanguage│   ├── CodeBlockWrapToggle│   ├── CodeBlockDownloadButton│   └── CodeBlockCopyButton├── CodeBlockSurface (Built-in or via CodeBlockContent)│   ├── Line Numbers (CSS counter, zero-DOM)│   ├── Fold Toggles & Diff Indicators (+ / -)│   ├── Code Tokens & Words│   └── CodeBlockLineActions (Hover action bar)└── CodeBlockExpandButton

Usage

import {  CodeBlock,  CodeBlockCopyButton,  CodeBlockHeader,  CodeBlockLanguage,  CodeBlockTitle,} from "@/components/ui/code-block"

<CodeBlock code={code} language="typescript" showLineNumbers>  <CodeBlockHeader>    <CodeBlockTitle>example.ts</CodeBlockTitle>    <CodeBlockLanguage />    <CodeBlockCopyButton className="ml-auto" />  </CodeBlockHeader></CodeBlock>

Examples

Git Diff & Patch Review

Display additions and removals with dedicated line gutters and background tints for reviewing pull requests and patch differences.

import { cookies } from "next/headers"
export async function getSession() {  // Legacy session extraction via raw cookie header  const rawCookie = headers().get("cookie")  // Secure token-based session resolution  const cookieStore = await cookies()  const token = cookieStore.get("session_token")?.value
  if (!token) return null  return verifySessionToken(token)}

Diagnostic Severity Levels

Surface inline compiler and linter diagnostics with error, warning, and info visual indicators.

interface UserProfile {  id: string  name: string  email: string  role?: "admin" | "editor" | "viewer"}
export function formatGreeting(user: UserProfile): string {  // TS2345: Argument of type 'undefined' is not assignable to parameter of type 'string'  const normalizedEmail = user.email.toLowerCase()
  // ESLint: prefer-optional-chain  if (user && user.role && user.role === "admin") {    return `Welcome, Administrator ${user.name} (${normalizedEmail})`  }
  return `Welcome back, ${user.name}!`}

Collapsible with Max Lines

Clamp lengthy code snippets to a clean maximum height with a smooth bottom gradient fade and floating expand button.

import { useQuery } from "@tanstack/react-query"import { z } from "zod"
const projectSchema = z.object({  id: z.string().uuid(),  name: z.string().min(1),  status: z.enum(["active", "archived", "draft"]),  stars: z.number().int().nonnegative(),  updatedAt: z.string().datetime(),})
type Project = z.infer<typeof projectSchema>
async function fetchProjects(): Promise<Project[]> {  const response = await fetch("/api/projects")  if (!response.ok) {    throw new Error(`Failed to fetch projects: ${response.statusText}`)  }  const data = await response.json()  return z.array(projectSchema).parse(data)}
export function useProjects() {  return useQuery({    queryKey: ["projects"],    queryFn: fetchProjects,    staleTime: 1000 * 60 * 5,    gcTime: 1000 * 60 * 30,    retry: 2,  })}

Action Toolbar with Wrap & Download

A complete header bar equipped with soft line-wrapping toggles, one-click file download, and clipboard copy affordances.

import { QueryClient } from "@tanstack/react-query"
export const queryClient = new QueryClient({  defaultOptions: {    queries: {      staleTime: 1000 * 60 * 5,      gcTime: 1000 * 60 * 60 * 24,      refetchOnWindowFocus: false,      retry: (failureCount, error) => {        if (error instanceof Response && error.status === 404) return false        return failureCount < 3      },    },    mutations: {      onError: (err) => {        console.error("Mutation failed with error:", err)      },    },  },})

API Reference

CodeBlock

The root container managing syntax highlighting, Shiki streaming, CSS counter state, and context providers.

CodeBlockContent

Composable surface that renders the code block inside an external scroll wrapper (e.g. ScrollArea).

CodeBlockHeader

Top toolbar header housing filename title, language tag, and action buttons.

CodeBlockTitle

Displays the file name or snippet label with standard typography.

CodeBlockLanguage

Displays the detected or specified syntax language badge.

CodeBlockCopyButton

Interactive clipboard button with animated copied state feedback.

CodeBlockDownloadButton

Downloads the current code block content as a local file.

CodeBlockWrapToggle

Toggles soft line-wrapping on and off.

CodeBlockExpandButton

Floating expand/collapse control rendered when maxLines clamps code block height.

CodeBlockLineActions

Render prop registering custom action controls on hovered/active code lines.

References

• ReUI Code Block Component
• ReUI Code Block Showcase & Variants
• Shiki Dual Themes & Syntax Highlighting
• CSS Counters (Zero-DOM Line Numbers)
• W3C WCAG 2.4.7 Focus Visible
• CSS content-visibility
• Unified Diff Format