js复制剪切板的代码，不兼容谷歌浏览器

下面的代码在谷歌浏览器里面无法向剪切板粘贴，我要怎么做呢？设置剪贴板内容
function browserCopy(text){            
            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您可以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();
                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);
            }
        }
找到这个链接，但我js不熟悉，还是不知道怎么用
处于安全原因，只能在onpaste事件里使用http://developer.apple.com/library/mac/#documentation/AppleApplications/Conceptual/SafariJSProgTopics/Tasks/CopyAndPaste.html