Function for_each_own_property 

fn for_each_own_property(
    cx: &mut JSContext,
    obj: HandleObject<'_>,
    f: impl FnMut(&mut JSContext, String, HandleValue<'_>),
) -> bool

Calls f(cx, key, value) for each own enumerable string/index property of obj. Returns false if a JSAPI call failed (an exception may be pending).