function addLink() {
     var selection = window.getSelection();
    pagelink = ". Read more at: " + document.location.href;
    copytext = selection + pagelink;
     newdiv = document.createElement('div');
     newdiv.style.position = 'absolute';
    newdiv.style.left = '-99999px';
    document.body.appendChild(newdiv);
    newdiv.innerHTML = copytext;
    selection.selectAllChildren(newdiv);
     window.setTimeout(function () {
        document.body.removeChild(newdiv);
    }, 100);
}
document.addEventListener('copy', addLink);