WordPress复制文章自动添加原创声明“文章来源于”

//转载请注明来源带原文链接
function add_copyright_text() { ?>
<script type='text/javascript'>
function addLink() {
 var body_element = document.getElementsByTagName('body')[0];
 var selection;
 selection = window.getSelection();
 var pagelink = "<br />转载请注明来源: <a href='"+document.location.href+"'>"+document.location.href+"</a>"; 
 var copy_text = selection + pagelink;
 var new_div = document.createElement('div');
 new_div.style.left='-99999px';
 new_div.style.position='absolute';
 body_element.appendChild(new_div );
 new_div.innerHTML = copy_text ;
 selection.selectAllChildren(new_div );
 window.setTimeout(function() {
 body_element.removeChild(new_div );
 },0);
}
document.oncopy = addLink;
</script>
<?php
}
add_action( 'wp_footer', 'add_copyright_text');