JS复制文本到剪切板

 function copyToClipboard(txt) {
     if(window.clipboardData) {
       window.clipboardData.clearData();
       window.clipboardData.setData("Text", txt);
       alert("Your request has been processed successfully.");
     } 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("Your request has been processed successfully.");
     }
    }