It takes one property argument, and returns the layer of which this property belongs to.

Get the layer of the selected property - After Effects Script .jsx

function LayerParentOfProperty(property) {
 try {
   return property.propertyGroup(property.propertyDepth);
 } catch (e) {
   return property;
 }
}

// example of use, gets the first selected property.
var selectedProperty = app.project.activeItem.selectedProperties[0];
if (selectedProperty) {
  alert(LayerParentOfProperty(selectedProperty).name);
 }