Flatten a nested array, accounting for varying levels of nesting. Ref: freecodecamp

steam-roller-algorithm.js

function steamrollArray(arr) {
  let flatArr = [];
  for(let item of arr){
    if(Array.isArray(item)){
      flatArr.push(...item.map(i => getValFromNestedArr(i)))
    }
    else {
      flatArr.push(item)
    }
  }
  return flatArr;
}

function getValFromNestedArr(arr){
  if(!Array.isArray(arr)){
    return arr;
  }
  else {
    return getValFromNestedArr(arr[0])
  }
}

//Tests
steamrollArray([[["a"]], [["b"]]]) //should return ["a", "b"].
steamrollArray([1, [2], [3, [[4]]]]) //should return [1, 2, 3, 4].
steamrollArray([1, [], [3, [[4]]]]) //should return [1, 3, 4].
steamrollArray([1, {}, [3, [[4]]]]) //should return [1, {}, 3, 4].