JavaScript reduce throwing error for more than two items

Question

I have this array:

const arr = [
  { someProp: [{ amount: 10 }]},
  { someProp: [{ amount: 12 }]},
];

and then this reduce fn:

con         


        

Answer 1

This is an alternative solution... Using Array.filter().

const arr = [{
    someProp: [{
      amount: 10
    }]
  },
  {
    someProp: [{
      amount: 12
    }]
  },
  {
    someProp: [{
      amount: -231
    }]
  },
  {
    someProp: [{
      amount: 21265
    }]
  },
  {
    someProp: [{
      amount: 1239
    }]
  },
  {
    someProp: [{
      amount: -6
    }]
  },
];
const sum = arr.filter((val, index) => {
  if (index > 0) {
    arr[index].someProp[0].amount = parseInt(val.someProp[0].amount) + parseInt(arr[index - 1].someProp[0].amount);
  }
  return index == arr.length - 1;
})[0].someProp[0].amount;

console.log(sum);