Copy to clipboard with Javascript

copy.js

function copyToClipboard(text, success) {
  if (navigator.clipboard && window.isSecureContext) {
    return navigator.clipboard.writeText(text).then(success).catch(err => {
      console.error('Failed to copy text: ', err);
    });
  } else {
    const textarea = document.createElement('textarea');
    textarea.value = text;

    document.body.appendChild(textarea);

    textarea.select();
    textarea.setSelectionRange(0, text.length);
    document.execCommand('copy');

    document.body.removeChild(textarea);

    success();
  }
}

copyToClipboard("Hello, world!", () => {
  alert('Copied to clipboard');
});