Filter and calculate the properties of objects from the same table using javascript

I hope my question is not asked too much in SO.

I have an array of 3 objects such as: :

const objStart1 = {
    'user': 1,
    'score': 15,
    'date': 'Monday'
}

const objStart2 = {
    'user': 1,
    'score': 7,
    'date': 'Friday'
}

const objStart3 = {
    'user': 2,
    'score': 5,
    'date': 'Monday'
}

I would like to group by date then calcul the average of the score by day (and delete user) and return a new array of objects like :

 const objStart1 = {
    'average': 10,
    'date': 'Monday'
}

const objStart2 = {
    'average': 7,
    'date': 'Friday'
}

It seems, we can use filter + reduce but my results are pathetic… Is there a good solution?

thank you in advance.

>Solution :

This should do the trick.
I put your items into an actual array, and I replaced Date with date.

const input = [
  {
    'user': 1,
    'score': 15,
    'date': 'Monday'
  },
  {
    'user': 1,
    'score': 7,
    'date': 'Friday'
  },
  {
    'user': 2,
    'score': 5,
    'date': 'Monday'
  },
]

const sumList = input.reduce((acc, current) => {
    if(!acc.find(obj => obj.date === current.date)) acc.push({date: current.date, sum: 0, count: 0})
    const currCounter = acc.find(obj => obj.date === current.date)
    currCounter.sum += current.score
    currCounter.count++
    return acc
  }, [])
  .map(({date, sum, count}) => ({ date, average: sum/count  }))

console.log(sumList)