clipboardCopy.js

function clipboardCopy(text) {
  // Use the Async Clipboard API when available. Requires a secure browsing
  // context (i.e. HTTPS)
  if (navigator.clipboard) {
    return navigator.clipboard.writeText(text).catch(function(err) {
      throw err !== undefined
        ? err
        : new DOMException('The request is not allowed', 'NotAllowedError')
    })
  }

  // ...Otherwise, use document.execCommand() fallback

  // Put the text to copy into a <span>
  var span = document.createElement('span')
  span.textContent = text

  // Preserve consecutive spaces and newlines
  span.style.whiteSpace = 'pre'

  // Add the <span> to the page
  document.body.appendChild(span)

  // Make a selection object representing the range of text selected by the user
  var selection = window.getSelection()
  var range = window.document.createRange()
  selection.removeAllRanges()
  range.selectNode(span)
  selection.addRange(range)

  // Copy text to the clipboard
  var success = false
  try {
    success = window.document.execCommand('copy')
  } catch (err) {
    console.log('error', err)
  }

  // Cleanup
  selection.removeAllRanges()
  window.document.body.removeChild(span)

  return success
    ? Promise.resolve()
    : Promise.reject(
        new DOMException('The request is not allowed', 'NotAllowedError'),
      )
}