FireFox IE js clipboard

function copyToClipboard(txt) { 
if(window.clipboardData) 
{  

window.clipboardData.clearData(); 
window.clipboardData.setData("Text", txt); 
} 
else if(navigator.userAgent.indexOf("Opera") != -1) 
{ 
window.location = txt; 
} 
else if (window.netscape) 
{ 
try {  
netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect"); 
} 
catch (e) 
{  

 alert("!!被浏览器拒绝！\n请在浏览器地址栏输入’about:config’并回车\n然后将’signed.applets.codebase_principal_support’设置为’true’");

} 
var clip = Components.classes[’@mozilla.org/widget/clipboard;1’].createInstance(Components.interfaces.nsIClipboard); 
  if (!clip) 
return; 
var trans = Components.classes[’@mozilla.org/widget/transferable;1’].createInstance(Components.interfaces.nsITransferable); 
if (!trans) 
return; 
trans.addDataFlavor(’text/unicode’); 
var str = new Object(); 
var len = new Object(); 
var str =
Components.classes["@mozilla.org/supports-string;1"].createInstance(Components.interfaces.nsISupportsString); 
var copytext = txt; 
str.data = copytext; 
trans.setTransferData("text/unicode",str,copytext.length*2); 
var clipid = Components.interfaces.nsIClipboard; 
if (!clip) 
return false; 
clip.setData(trans,null,clipid.kGlobalClipboard); 
} 
return true; 
}