Handling POSTed data from forms

I tried the demo on my Espruino WiFi 1.1 and it worked as expected. Except I am wondering about that when I click one of the check boxes that control the LEDs, then click Submit, the page is reloaded and the check box value then becomes unchecked.
Is there a way to modify the code so that a check box stays checked when reloading the page? That could perhaps be done so that the value of the check box is saved and when reloading the page, that check box stays checked?
that brings me to the question if the page is loaded before or after postDATA is updated?