function ddChange()
{
	var name;
	for (var i=0; i<dropdowns.length; i++)
	{ 
		if (this.id == dropdowns[i].id)
		{
			name = dropdowns[i].name;
			break;
		}
	}
	if (ddVal(this.id) != null)
		location.href = location.pathname + '?' + name + '=' + ddVal(this.id);
}

function ddVal(id)
{
	var el = dID(id);
	var val = el.selectedIndex == 0 ? null : el.options[el.selectedIndex].value;
	return val;
}

function dID(id) { return document.getElementById(id); }

function timeOfDay(time)
{
	var date = ddVal(dropdownId.date);
	location.href = location.pathname + '?timeofday=' + time + (date?'&date=' + date:'');
}

var dropdowns = [
					{name:'date',id:dropdownId.date},
					{name:'program',id:dropdownId.program}
				];
for (var i=0; i<dropdowns.length; i++) { dID(dropdowns[i].id).onchange = ddChange; }