<form id="math" action="">
	<fieldset>
	<legend>MathParser</legend>
	<label>Expresso</label><input type="text" name="exp" value="userFunction(1, 1) + 1" /><br /><br />
	<input type="submit" value="MathParser.parse()" />
	</fieldset>
</form>

<script type="text/javascript">
//<![CDATA[

var parser = new MathParser(), f = document.forms.math;

parser.add("userFunction", function(n, m){
	return n + m;
});

addEvent(f, "submit", function(e){
	try{
		alert(parser.parse(f.exp.value));
	}catch(e){
		alert("Error: " + e);
	}
	return false;
});

//]]>
</script>