Javascript 'classe'

<script language="JavaScript">
Rekenen = {};

Rekenen.telOp = function(getal1, getal2)
{
	alert(getal1 + getal2);
}

Rekenen.telVerminderen = function(getal1, getal2)
{
	alert(getal1 - getal2);
}

Rekenen.telKeer = function(getal1, getal2)
{
	alert(getal1 * getal2);
}

Rekenen.telDelen = function(getal1, getal2)
{
	alert(getal1 / getal2);
}

var Ding = document.form.ding.value;
if(Ding == "telOp")
{
	Rekenen.telOp(4, 2);
}
else
{
	if(Ding == "telVerminderen")
	{
		Rekenen.telVerminderen(4, 2);
	}
	else
	{
		if(Ding == "telKeer")
		{
			Rekenen.telKeer(4, 2);
		}
		else
		{
			if(Ding == "telDelen")
			{
				Rekenen.telDelen(4, 2);
			}
			else
			{
				alert("Er is een fout..!");
			}
		}
	}
}
</script>
<form name="form" method="post" action="">
  <select name="Ding" id="Ding">
    <option value="telOp">Optellen</option>
    <option value="telVerminderen">Verminderen</option>
    <option value="telDelen">Delen</option>
    <option value="telKeer">keer</option>
  </select>
  <input type="submit" name="Submit" value="Submit" onClick="Javascript: Rekenen;">
</form>

<script language="JavaScript">
Rekenen = {};
 
Rekenen.telOp = function(getal1, getal2)
{
	alert(getal1 + getal2);
}
 
Rekenen.telVerminderen = function(getal1, getal2)
{
	alert(getal1 - getal2);
}
 
Rekenen.telKeer = function(getal1, getal2)
{
	alert(getal1 * getal2);
}
 
Rekenen.telDelen = function(getal1, getal2)
{
	alert(getal1 / getal2);
}
 
var Ding = document.form.ding.value;
if(Ding == "telOp")
{
	Rekenen.telOp(4, 2);
}
else
{
	if(Ding == "telVerminderen")
	{
		Rekenen.telVerminderen(4, 2);
	}
	else
	{
		if(Ding == "telKeer")
		{
			Rekenen.telKeer(4, 2);
		}
		else
		{
			if(Ding == "telDelen")
			{
				Rekenen.telDelen(4, 2);
			}
			else
			{
				alert("Er is een fout..!");
			}
		}
	}
}
</script>
<form name="form" method="post" action="">
  <select name="Ding" id="Ding">
    <option value="telOp">Optellen</option>
    <option value="telVerminderen">Verminderen</option>
    <option value="telDelen">Delen</option>
    <option value="telKeer">keer</option>
  </select>
  <input type="submit" name="Submit" value="Submit" onClick="Javascript: Rekenen;">
</form>