Count object literal duplicates in an array

Question

I have a simple task. I've got to do an ATM in javascript. However, I don't know, how whether add 1 to an object if exists or if counting object duplicates and then showing them.

This is my main function.

const getCash = (credit, saved) => {
  let returnedCash = []
  for (const obj of saved) {
    for (let i = 0; i < obj.amount; i++) {
      if (credit > 0){
        if (credit - obj.value < 0) break
        credit -= obj.value
        returnedCash.push({value: obj.value})
      }
    }
  }
  return returnedCash
}

And then returns something like this

[{value: 50}, {value: 50}, {value: 30}]

Know how to do both? And what is more a good practice?