Why is useState not triggering re-render?

Question

I\'ve initialized a state that is an array, and when I update it my component does not re-render. Here is a minimal proof-of-concept:

function App() {
  const         


        

Answer 1

You need to copy numbers like so let old = [...numbers];

useState doesn't update the value only if it has changed so if it was 44 and it became 7 it will update. but how can it know if an array or object have changed. it's by reference so when you do let old = numbers you are just passing a reference and not creating a new one