Pass parameter to filter function in Spry framework?

Question

I have a Spry filter function which works:

function ffRed(ds, row, index){ var c = row["color"]; return c == 'red' ? row : null; };

Which is toggled by function called from the click handler of a checkbox:

function ToggleFilter(enable, f)
{
  if (enable)
ds1.addFilter(f, true);
  else
ds1.removeFilter(f, true);
}

Where the check box is onclick="ToggleFilter(this.checked, ffRed);"

I would rather pass a parameter from the checkbox, so I can use the same handler and filter for all the checkboxes and pass which color (e.g. 'red') from the click handler.

I can pass the parameter to the ToggleFilter function no problem, but how to pass it to the filterFunction?

Like this made some sense:

function ffColor(ds, row, index, clr){ var c = row["color"]; return c == clr ? row : null; };

Except this does not do it: ds1.addFilter(f, true, clr) assuming that clr has been passed the string 'red' from the click handler. That part works, but I am obviously passing it to the filter function wrong.