This line will cause a new array to be created on every render, which may cause performance issues, so it's always better to avoid it. There are a couple of techniques which can be used to avoid the recomputation:

1. Instead of creating an array directly, we can place it inside useMemo hook.
2. Sometimes the array doesn't depend on anything (props / state / etc.). In those cases it can be created outside a component and used as a constant.
3. When it comes to class names, there's a library classnames which can be used. It produces a string which is safe to use as a prop.

But none of these should be used here, because after introducing gap, this component will have only one class.