Optionalbackdropthe dimming backdrop (clicking it closes).
Optionalopenclass toggled for the open transition (default "open").
Optionalhidems to wait before hard-hiding on close (matches the CSS transition; default 220).
Optionalinertpage-chrome elements to make inert while open (focus-trap + AT hide).
Optionalinitialelement to focus on open (e.g. the close button).
Optionaloncalled on open / close (e.g. cart.reload() before showing).
OptionalonOptionalrafinjectables (default the globals) — tests pass sync stand-ins.
Optionalset
the sliding panel.