Result

<div class="foo bar"></div>

<div class="foo raa"></div>

Source

<ul id="container">
	<li>
		<div class="foo bar"></div>
		<div class="foo bar"></div>
		<div class="foo bar"></div>
	</li>
	<li> 
		<div class="foo raa"></div>
		<div class="foo raa"></div>
		<div class="foo raa"></div>
	</li>
</ul>


<script>
	$(document).ready(function(){
		$('ul#container li').each(function(){
			$(this).find('.foo').hide();
			$(this).find('.foo:first').show();
		});
	});
</script>