if(navigator.userAgent.indexOf("MSIE") > -1){ //Internet Explorer
document.write('<!-'+'-[if IE]>');
document.write('<a href="" onclick="window.external.AddFavorite(\'http://www.at-creditcard.net/index.html\',\'＠クレジットカード\')">');
document.write('<img src="http://www.at-creditcard.net/img/favorite.gif" alt="" /></a>');
document.write('<![endif]-'+'->');
}

else if(navigator.userAgent.indexOf("Firefox") > -1){ //Firefox
document.write('<a href="" onclick="window.sidebar.addPanel(\'＠クレジットカード\',\'http://www.at-creditcard.net/index.html\',\'\');">');
document.write('<img src="http://www.at-creditcard.net/img/favorite.gif" alt="" /></a>');
}

else if(navigator.userAgent.indexOf("Opera") > -1){ //Opera
document.write('<a href="http://www.at-creditcard.net/index.html" rel="sidebar" title="＠クレジットカード"><img src="http://www.at-creditcard.net/img/favorite.gif" alt="" /></a>');
}

else { //該当なし
document.write('お気に入りに登録する');
}