What is the use case for the useTransition props initial and update?

[steschwa]

useTransition has a range of props as shown in the documentation (from https://www.react-spring.dev/docs/components/use-transition#reference):

Typically if i want to animate e.g. a dialog open/close state (passed item to useTransition is of type boolean) i only use from, enter and exit. Here's how i understand how they behave:

• from: "starting state" of the animation. Get applied once the item changes to true
• enter: "idle state" of the animation. These indicate the desired props and are animated from from
• exit: "exit state" of the animation. Animated to from enter if item changes from true to false. After reaching the animation finished, the component gets unmounted

But what is the use case for the initial and update props? If i use initial (next to from, enter and exit) nothing changes