Top-tompak,
<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<script src="http://code.jquery.com/jquery-latest.min.js"></script>
</head>
<body>
<div id="item">адам</div>
<script>
var val = 'а[^a]*$';
var re = new RegExp(val, 'i');
if (re.test($('#item').text()) ) {
alert('Ok!');
};
</script>
</body>
</html>