the following is the code. but it doesn't work. what's wrong with it? thank you.
      <head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
     <title>no title</title>
   <script type="text/javascript">
      function copyToClipBoard(content){
 var clipBoardContent = ''; 
clipBoardContent = content;
 window.clipboardData.setData("Text",clipBoardContent);
 alert('have copied to the clipboard');
}
 <body>
<textarea rows="4" cols="60" id="url">www.example.com</textarea>
     <input type="button" value="click me" onclick="copyToClibBoard (document.getElementById   ('url').value);" />
</body>
 
    