javascript - find repeated values in an array of objects

Question

(This question already has answers here): question from:https://stackoverflow.com/questions/66051491/find-repeated-values-in-an-array-of-objects

Answer 1

Maybe use reduce?

const newArr = Object.values(arr.reduce((acc, { date, state, duration }) => {
  acc[date+state] = (acc[date+state] || 0) + +duration
  return acc
}, {}))

Or something like

arr.reduce((acc, { date, state, duration }) => {
  if (!acc[state]) {
    acc[state] = {}
  }
  acc[state][date] = (acc[state][date] || 0) + +duration
  return acc
}, {})

And some logic with Object.keys() and sort()