javascript - Copy to Clipboard in Chrome Extension

Question

I'm making an extension for Google Chrome and I have hit a snag.

I need to copy a readonly textarea's content to the clipboard on click in the popup. Does anyone know the best way to go about this with pure Javascript and no Flash? I also have jQuery loaded in the extension, if that helps any. My current (non-working) code is...

function copyHTMLCB() {
$('#lb_html').select();
$('#lb_html').focus();
textRange = document.lb_html_frm.lb_html.createTextRange();
textRange.execCommand("RemoveFormat");
textRange.execCommand("Copy");
alert("HTML has been copied to your clipboard."); }

Answer 1

All credit goes to joelpt, but in case anyone else needs this to work in pure javascript without jQuery (I did), here's an adaptation of his solution:

function copyTextToClipboard(text) {
  //Create a textbox field where we can insert text to. 
  var copyFrom = document.createElement("textarea");

  //Set the text content to be the text you wished to copy.
  copyFrom.textContent = text;

  //Append the textbox field into the body as a child. 
  //"execCommand()" only works when there exists selected text, and the text is inside 
  //document.body (meaning the text is part of a valid rendered HTML element).
  document.body.appendChild(copyFrom);

  //Select all the text!
  copyFrom.select();

  //Execute command
  document.execCommand('copy');

  //(Optional) De-select the text using blur(). 
  copyFrom.blur();

  //Remove the textbox field from the document.body, so no other JavaScript nor 
  //other elements can get access to this.
  document.body.removeChild(copyFrom);
}