[Vuejs]-Vue update array state using the composition api

reactive doesn’t work with Arrays. Seems to be a limitation of the composition api. You can read a similar discussion here.

Use ref instead of reactive, it should work fine. I have built a few apps like this and can confirm it working.
So write: const state = ref<Array<Notification>>([]);, you will have it working. And as a rule of thumb, use ref for anything but objects, that’s when you want to use reactive. It’s more complex than that but if you use them like this, it will always work.