Reduce giving errors for multidimensional array sum js

Question

Getting error arr.reduce is not a function for multidimensional arrays - works fine for simple arrays - not sure what's going wrong?

let arr = [4, [5, 7]]
let sum = 0

const calculateSum = (arr) => {
  return arr.reduce(function(acc, currentVal) {
    const isEntryArray = Array.isArray(currentVal)
    if (isEntryArray) {
      acc= acc + calculateSum(currentVal)
    } else {
      acc = acc + currentVal
    }
    return acc
  }, 0)
}
console.log(calculateSum(arr))
console.log(sum) ```

Running this in the browser console doesn't give an error... perhaps your last edit fixed it? — Take-Some-Bytes
– Take-Some-Bytes, Commented Dec 24, 2022 at 5:15

Andy · Accepted Answer · 2021-12-29 00:22:11Z

3

Instead of using a recursive function flatten the array and then use reduce to calculate the sum.

const arr = [4, [5, 7, [12, [1, 2]]]];

function calculateSum(arr) {
  return arr.flat(Infinity).reduce(function (acc, c) {
    return acc + c;
  }, 0);
}

console.log(calculateSum(arr));

edited Dec 29, 2021 at 0:22

answered Dec 29, 2021 at 0:15

Andy

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1 Comment

zer00ne Over a year ago

.flat(Infinity) is slick.

charlietfl · Accepted Answer · 2021-12-29 00:14:47Z

0

You are passing in a boolean not an array when you do:

acc= acc + calculateSum(isEntryArray)
                        // ^^^ from Array.isArray()

I believe what you wanted was to pass in the current sub array

acc= acc + calculateSum(currentVal)

answered Dec 29, 2021 at 0:14

charlietfl

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