Clipboard API Usage Guide with Claude Code

Improve User Experience With the Clipboard API

One-click code copies, rich-text pasting… the Clipboard API significantly improves the usability of web apps. With Claude Code, you can quickly build implementations that take browser compatibility and security into account.

Copy Button for Code Blocks

> Add a copy button to code blocks.
> Show a "Copied" feedback state after the click.

// components/CopyButton.tsx
import { useState, useCallback } from 'react';

interface CopyButtonProps {
  text: string;
}

export function CopyButton({ text }: CopyButtonProps) {
  const [copied, setCopied] = useState(false);

  const handleCopy = useCallback(async () => {
    try {
      await navigator.clipboard.writeText(text);
      setCopied(true);
      setTimeout(() => setCopied(false), 2000);
    } catch (err) {
      // Fallback
      fallbackCopy(text);
      setCopied(true);
      setTimeout(() => setCopied(false), 2000);
    }
  }, [text]);

  return (
    <button
      onClick={handleCopy}
      className="absolute right-2 top-2 rounded bg-gray-700 px-2 py-1 text-xs text-white
        transition-colors hover:bg-gray-600"
      aria-label={copied ? 'Copied' : 'Copy code'}
    >
      {copied ? '✓ Copied' : 'Copy'}
    </button>
  );
}

function fallbackCopy(text: string): void {
  const textarea = document.createElement('textarea');
  textarea.value = text;
  textarea.style.position = 'fixed';
  textarea.style.opacity = '0';
  document.body.appendChild(textarea);
  textarea.select();
  document.execCommand('copy');
  document.body.removeChild(textarea);
}

Copying Rich Text

// utils/clipboard.ts
export async function copyRichText(html: string, plainText: string): Promise<void> {
  if (!navigator.clipboard?.write) {
    fallbackCopy(plainText);
    return;
  }

  const htmlBlob = new Blob([html], { type: 'text/html' });
  const textBlob = new Blob([plainText], { type: 'text/plain' });

  const item = new ClipboardItem({
    'text/html': htmlBlob,
    'text/plain': textBlob,
  });

  await navigator.clipboard.write([item]);
}

// Usage example: copying table data
async function copyTableAsHtml(data: string[][]) {
  const html = `<table>${data.map(row =>
    `<tr>${row.map(cell => `<td>${cell}</td>`).join('')}</tr>`
  ).join('')}</table>`;

  const text = data.map(row => row.join('\t')).join('\n');
  await copyRichText(html, text);
}

Reading From the Clipboard

// Handle images on paste
async function handlePaste(e: ClipboardEvent): Promise<void> {
  const items = e.clipboardData?.items;
  if (!items) return;

  for (const item of items) {
    if (item.type.startsWith('image/')) {
      e.preventDefault();
      const blob = item.getAsFile();
      if (blob) {
        const url = URL.createObjectURL(blob);
        insertImage(url);
      }
    }
  }
}

// Check permissions via the Permissions API
async function checkClipboardPermission(): Promise<boolean> {
  try {
    const result = await navigator.permissions.query({
      name: 'clipboard-read' as PermissionName,
    });
    return result.state === 'granted' || result.state === 'prompt';
  } catch {
    return false;
  }
}

Share URL Copy Feature

function ShareUrl({ url, title }: { url: string; title: string }) {
  const [copied, setCopied] = useState(false);

  const handleCopy = async () => {
    await navigator.clipboard.writeText(url);
    setCopied(true);
    setTimeout(() => setCopied(false), 3000);
  };

  return (
    <div className="flex items-center gap-2 rounded-lg border p-3">
      <input
        type="text"
        value={url}
        readOnly
        className="flex-1 bg-transparent text-sm outline-none"
      />
      <button
        onClick={handleCopy}
        className="rounded bg-blue-600 px-3 py-1 text-sm text-white hover:bg-blue-700"
      >
        {copied ? 'Copied!' : 'Copy URL'}
      </button>
    </div>
  );
}

Security Considerations

// Paste with sanitization
function sanitizePastedContent(html: string): string {
  const div = document.createElement('div');
  div.innerHTML = html;

  // Remove script-like tags
  div.querySelectorAll('script, iframe, object, embed').forEach(el => el.remove());

  // Remove event handler attributes
  div.querySelectorAll('*').forEach(el => {
    Array.from(el.attributes)
      .filter(attr => attr.name.startsWith('on'))
      .forEach(attr => el.removeAttribute(attr.name));
  });

  return div.innerHTML;
}

Summary

Leveraging the Clipboard API can significantly improve UX for things like code block copying and sharing features. With Claude Code, you can build robust implementations that include fallback handling and security measures. Combined with the Web Share API, you can provide even more flexible sharing. Don’t forget to consider performance optimization too. For detailed specs, see the MDN Web Docs.