Copy text to clipboard: Cannot read properties of undefined reading ‘writeText’

The use of navigator.clipboard requires a secure origin. So if your dev environment is being served over HTTP, then the clipboard method won’t be available.

According to MDN Clipboard docs

This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

Maybe you could check if this method is available with window.isSecureContext, and disable the Copy Text button accordingly.

Workaround

The best option is to use HTTPS in your dev environment.

But since you asked for a workaround, here’s a (very hacky) working method. Using Document.exec command, which is no longer recommended, in favour of ClipboardAPI.

function unsecuredCopyToClipboard(text) {
  const textArea = document.createElement("textarea");
  textArea.value = text;
  document.body.appendChild(textArea);
  textArea.focus();
  textArea.select();
  try {
    document.execCommand('copy');
  } catch (err) {
    console.error('Unable to copy to clipboard', err);
  }
  document.body.removeChild(textArea);
}

Usage

You can then just check if !navigator.clipboard and call the fallback method, otherwise continue with the normal navigator.clipboard.writeText(...) function. For example:

const unsecuredCopyToClipboard = (text) => { const textArea = document.createElement("textarea"); textArea.value=text; document.body.appendChild(textArea); textArea.focus();textArea.select(); try{document.execCommand('copy')}catch(err){console.error('Unable to copy to clipboard',err)}document.body.removeChild(textArea)};

/**
 * Copies the text passed as param to the system clipboard
 * Check if using HTTPS and navigator.clipboard is available
 * Then uses standard clipboard API, otherwise uses fallback
*/
const copyToClipboard = (content) => {
  if (window.isSecureContext && navigator.clipboard) {
    navigator.clipboard.writeText(content);
  } else {
    unsecuredCopyToClipboard(content);
  }
};

<button onClick="buttonPress()">➡️ Copy Message to Clipboard</button>

<script type="text/javascript"> const buttonPress = () => { copyToClipboard('Hello World!'); console.log('Clipboard updated 📥\nNow try pasting!'); }; </script>