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) {
            return "您的firefox安全限制限制您进行剪贴板操作，请打开'about:config'将signed.applets.codebase_principal_support'设置为true'之后重试";
        }
        var clip = Components.classes['@mozilla.org/widget/clipboard;1'].createInstance(Components.interfaces.nsIClipboard);
        if (!clip) return false;
        var trans = Components.classes['@mozilla.org/widget/transferable;1'].createInstance(Components.interfaces.nsITransferable);
        if (!trans) return false;
        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 (!clipid)
        return false;
        clip.setData(trans,null,clipid.kGlobalClipboard);
    }
    return true;
}