The web has limited support for Right-to-Left (RTL) layouts. It does a pretty good job when it comes to text alignment and text rendering, but lacks the features needed to build fully RTL compatible UIs. Therefore, Yoga has adopted Start and End values for Margin, Padding, Border, and Position properties.

Direction

With Start and End, you can specify these properties in your UI without having to think about whether your item will show up on the left or the right side of the screen (depending on the person’s language setting). Yoga automatically handles this for you.

The Direction property controls this behavior. Direction defaults to Inherit on all nodes except the root which defaults to LTR. It is up to you to detect the user’s preferred direction (most platforms have a standard way of doing this) and setting this direction on the root of your layout tree.