Code Block — logic2b/ui

bash

npx logic2b@latest add code-block

import { CodeBlock } from "@/components/ui/code-block"

export default function CodeBlockDemo() {
  return (
    <CodeBlock
      language="bash"
      code="npx logic2b@latest add code-block"
      className="w-full max-w-md"
    />
  )
}

Installation

npx logic2b@latest add code-block

Working with an AI assistant? Copy this prompt into Claude Code, Cursor or Copilot — it carries the install steps, a no-CLI fallback and a verification checklist.

Add the "code-block" item from the logic2b ui registry (https://ui.logic2b.com) to this project. Follow every step and verify at the end.

## Steps

1. If the project has no `components.json` yet, set up logic2b ui first:

   ```bash
   npx logic2b@latest init
   ```

2. Install the item (the CLI resolves registry dependencies automatically):

   ```bash
   npx logic2b@latest add code-block
   ```

3. Install any npm dependencies the command prints.

## If the CLI is not available

Do it manually from the registry payload:

1. Fetch https://ui.logic2b.com/r/code-block.json.
2. Write every entry in `files[]` to its mapped project path (see below).
3. Repeat (recursively) for each name in `registryDependencies`.
4. Install every package listed in `dependencies` across those payloads.

## Registry reference

- Index of every item: https://ui.logic2b.com/r/index.json
- Item payload (full source): https://ui.logic2b.com/r/<name>.json
- Usage examples per item: https://ui.logic2b.com/r/demos/index.json → https://ui.logic2b.com/r/demos/<demo>.json
- Docs index for agents: https://ui.logic2b.com/llms.txt (full docs: https://ui.logic2b.com/llms-full.txt)
- Every docs page is Markdown when you append `.md` to its URL.

Registry file paths map to project paths like this:
- `ui/*` → `@/components/ui/*`
- `blocks/<name>/*` → `@/components/*`
- `charts/*` → `@/components/charts/*`
- `hooks/*` → `@/hooks/*`
- `lib/utils.ts` → `@/lib/utils.ts`
- `theme.css` → next to the project's Tailwind entry stylesheet

## Conventions (do not break these)

- Tailwind CSS v4 (CSS-first config; no tailwind.config.js needed) and React 19.
- All colors go through semantic tokens (`bg-primary`, `text-muted-foreground`,
  `border-border`, …). Never hardcode hex/oklch values in components.
- Dark mode is class-based: toggle `.dark` on `<html>`.
- Icons come from lucide-react.

## Verify before finishing

1. The dev server starts and the app renders without console errors.
2. TypeScript compiles (`tsc --noEmit` or the framework's check).
3. Components use the theme: a `<Button>` shows the primary token color,
   and toggling `.dark` on `<html>` switches the palette.

Install the dependencies:

npm install lucide-react

Copy into ui/code-block.tsx:

"use client"

import * as React from "react"
import { CheckIcon, CopyIcon } from "lucide-react"

import { cn } from "@/lib/utils"

export interface CodeBlockProps
  extends Omit<React.ComponentProps<"div">, "children"> {
  /** The code to render and copy. */
  code: string
  /** Optional language label shown in the header (display only — no highlighting). */
  language?: string
}

/**
 * A styled code container with a one-click copy button. Dependency-free (no
 * syntax highlighter): renders the code verbatim in a `<pre>` and copies it via
 * the Clipboard API, with a copied-state affordance.
 */
function CodeBlock({ className, code, language, ...props }: CodeBlockProps) {
  const [copied, setCopied] = React.useState(false)
  const timer = React.useRef<ReturnType<typeof setTimeout> | undefined>(
    undefined
  )

  React.useEffect(() => () => clearTimeout(timer.current), [])

  const copy = async () => {
    try {
      await navigator.clipboard.writeText(code)
      setCopied(true)
      clearTimeout(timer.current)
      timer.current = setTimeout(() => setCopied(false), 2000)
    } catch {
      // Clipboard unavailable (insecure context / denied) — no-op.
    }
  }

  const CopyButton = (
    <button
      type="button"
      onClick={copy}
      aria-label={copied ? "Copied" : "Copy code"}
      className={cn(
        "text-muted-foreground hover:bg-accent hover:text-foreground inline-flex size-7 items-center justify-center rounded-md transition-colors outline-none",
        "focus-visible:ring-ring/50 focus-visible:ring-[3px]"
      )}
    >
      {copied ? (
        <CheckIcon className="size-3.5" />
      ) : (
        <CopyIcon className="size-3.5" />
      )}
    </button>
  )

  return (
    <div
      data-slot="code-block"
      className={cn(
        "bg-muted/40 relative overflow-hidden rounded-lg border",
        className
      )}
      {...props}
    >
      {language ? (
        <div className="flex items-center justify-between border-b px-3 py-1.5">
          <span className="text-muted-foreground font-mono text-xs">
            {language}
          </span>
          {CopyButton}
        </div>
      ) : (
        <div className="absolute top-1.5 right-1.5 z-10">{CopyButton}</div>
      )}
      <pre
        className={cn(
          "overflow-x-auto p-4 text-sm leading-relaxed",
          !language && "pr-11"
        )}
      >
        <code className="font-mono">{code}</code>
      </pre>
    </div>
  )
}

export { CodeBlock }

Usage

import { CodeBlock } from "@/components/ui/code-block"

<CodeBlock language="tsx" code={`const answer = 42`} />

The copy button writes code to the clipboard and shows a checkmark for two seconds. Omit language to render a bare block with a floating copy button in the corner.

Highlighting

CodeBlock is deliberately dependency-free and does not ship a syntax highlighter. To add highlighting, render your highlighter’s output inside the <pre> — e.g. pass Shiki/Prism-generated HTML — or wrap this component. Keeping the base free of a highlighter means it stays tiny and framework-agnostic.

API

Prop	Type	Default
`code`	`string`	— (required)
`language`	`string` (display label)	—
…props	`React.ComponentProps<"div">`	—