domA.style.display = "none"; domA.style.display = "block;
I could not find such functions in the library, but I guess they must have it somewhere.
<html>
<head>
<script src="http://closure-library.googlecode.com/svn/trunk/closure/goog/base.js" type="text/javascript"></script>
<script language="JavaScript">
goog.require('goog.style');
</script>
</head>
<body>
<div id="myElement">test</div>
</body>
</html>
<script>
goog.style.setStyle(goog.dom.$("myElement"), "display", "none");
// or
goog.style.showElement(goog.dom.$("myElement"), false);
</script>