I couldn't access document from background.js when migrated to V3. I want to save some data to clipboard. Anyone have idea about this issue? i tried with severel ways to do this.

   var copyFrom = document.createElement("textarea");
   copyFrom.textContent = "data to copy";
   document.body.appendChild(copyFrom);
   copyFrom.select(); 
   document.execCommand('copy');  
   copyFrom.blur(); 
   document.body.removeChild(copyFrom);

I got this error