setFilter old variable - TypeError: Cannot read property '1' of undefined

[jaekunchoi]

I'm trying to use number range filter with setFilter similar to what's being used in https://codesandbox.io/s/github/tannerlinsley/react-table/tree/master/examples/filtering
The problem is setFilter old variable is undefined somehow.

setFilter((old) => { 
  return [val ? parseInt(val, 10) : undefined, old[1]] 
})

How can I ensure old variable is defined?

[jaekunchoi]

nevermind, I just had to put default empty array for old variable old = []

Final answer

setFilter((old = []) => { 
  return [val ? parseInt(val, 10) : undefined, old[1]] 
})