Why does Checkbox's update:modelValue has the type boolean | "indeterminate"?

[tuananhlai]

First of all, I just want to thank the Reka UI team for creating such a high quality component library for Vue. The library you guys provided has been very helpful to me as a developer.

Getting back to topic, I noticed that the type for Checkbox's update:modelValue event parameter has the type boolean | "indeterminate", but indeterminate doesn't seem to be emitted anywhere in the component code. This is quite annoying as an user because you can't assign update:modelValue event parameter to a boolean variable without type casting.

I'd be much appreciated if you can help me understand the reasoning behind this design decision. Thank you very much in advanced.

[epr3]

The indeterminate state is based on the WAI ARIA tri-state checkbox pattern: https://www.w3.org/WAI/ARIA/apg/patterns/checkbox/