<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
</head>
<body>
<textarea id="myTextArea" name="" rows="15" cols="35">
;)
:)
:-)
Или даже больше
*beer**beer*
*beer*
</textarea>
<script>
var my_text = document.getElementById('myTextArea'),
count_smiles=(my_text.value.split(/:-\)|\*beer\*|:\)|;\)/).length-1);
alert(count_smiles);
</script>
</body>
</html>