Custom zoom script

I found a script by Jongware at InDesign Secrets for fitting on a page and then zooming:

app.layoutWindows[0].zoom(ZoomOptions.FIT_PAGE);

try {app.layoutWindows[0].zoomPercentage = Number(app.activeScript.name.match(/\d+/)[0]);} catch (e) {};

I modified it to fit on the spread and then zoom:

app.layoutWindows[0].zoom(ZoomOptions.FIT_SPREAD);

try {app.layoutWindows[0].zoomPercentage = Number(app.activeScript.name.match(/\d+/)[0]);} catch (e) {};

It works great for my needs if no items are selected on the spread.  However, the problem is that when a frame(s) is selected it doesn't center the spread anymore.  The center point (vertically and horizontally) becomes the center of the frame or group of frames selected.  Would anyone know how to modify this script so that it it is frame selection independant?  Thanks.