Computed re render is inconsistent. about core

[LinusBorg]

Correct analysis by @warunacds

Your computed returns a copy of the reactive array, and that copy is plain, non-reactive. changing it (i.e. by pushing to it) will not trigger any reactive effects.

[warunacds]

As I understand what's happening here, plusOne is a computed property of count that returns a copy of count, so when you change plusOne, it wants to trigger Vue's reactivity system.

Changing the handleClick function to change count directly will trigger the reactivity system.

const handleClick = () => {
  count.value.push(123);
}

as per

function onChange() {
  plusOne.value.push(321);
  msg.value = '';
}

When msg changes, DOM get updates, and that will render the new values in plusOne