dynamicky select box

<script type="text/javascript">
		function populate(o)
		{
			d=document.getElementById('de');
			if(!d){return;}			
			var mitems=new Array();
			mitems['Main Courses']=['Burger Meals','Breakfast','Steaks','Fish Dishes','Vegetarian Dishes'];
			mitems['Snacks']=['Brownies','Cookies'];
			mitems['Drinks']=['Shakes','Sodas','Cocktails','Juices'];
			mitems['Salads']=['Tuna Salad','Cesar Salad','Green Salad','Prawn Salad'];
			mitems['Deserts']=['Pancakes','Waffles','Ice Cream','Fresh Fruit'];
			d.options.length=0;
			cur=mitems[o.options[o.selectedIndex].value];
			if(!cur){return;}
			d.options.length=cur.length;
			for(var i=0;i<cur.length;i++)
			{
				d.options[i].text=cur[i];
				d.options[i].value=cur[i];
			}
		}
    </script>
	<form action="spracuj_selectbox.php" method="post">
	<label for="or">Our menu:</label>
	<select name="or" id="or" onchange="populate(this)">
		<option value="Main Courses">Main Courses</option>
		<option value="Snacks">Snacks</option>
		<option value="Salads">Salads</option>
		<option value="Drinks">Drinks</option>
		<option value="Deserts">Deserts</option>
	</select>
	<label for="de">Select:</label>
	<select name="de" id="de">
	</select>
	<input type="submit" value="odoslat" />
</form>