Submit GET form using javascript?

[resting]

I have this problem.

 

The user selects the size from a drop down menu.

 

On submit, the value for size is get by javascript:

 

var size = document.getElementById('size').value
var url   = "cart.php?category=" + category + "&id=" + id + "&size=" + size;

 

i want the form to submit with the 3 variables (category, id and size). I could generate the url with javascript and redirect with windows.location. But is it possible to submit with the GET method instead?

 

I have to include the full url when I submit from javascript right? That will make the script difficult to move to another location.