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);   
         alert("复制成功！")   
    }   
}