剪切板，真实可用，兼容IE和FF

function saveToClipboard(txt) {      if(window.clipboardData) {      window.clipboardData.clearData();      window.clipboardData.setData("Text", txt);     alert("已经复制到剪切板！")    } else if(navigator.userAgent.indexOf("Opera") != -1) {      window.location = txt;      alert("已经复制到剪切板！");   } 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("已经复制到剪切板！")      }}