layer.z < number>

The z property of a layer defines its position in space, also known as depth. The larger this value, the further away the object is from the point of view.

Remember that you will have to enable perspective on a parent layer before you can see this effect. Also note the z property is different from layer.index (z-index) which defines the order for layers when they all have the same z value.
译：Z一层的属性定义了它在空间位置,也被称为深度。 这个值越大, 对象的距离就越远。
记住，在你能看到这种效果之前，你必须在父母的层面上启用透视。还请注意，Z属性不同于layer.index (z-index)定义层的命令时，他们都有相同的Z值。

layerA = new Layer
layerA.z = 500