I have to create a function that receives an array in which every element is a number, or it can be another array with numbers inside, for example : const array = [1, [2, [3,4]], [5,6], 7]; The function should count all the values and return it countArray(array); --> should return 28 because (1 + 2 + 3 + 4 + 5 + 6 + 7)
I tried this
const array = [1, [2, [3,4]], [5,6], 7];
var countArray = function(array) {
let sum = 0
for (let i = 0; i < array.length; i++) {
if (Array.isArray(array[i])) {
countArray(array[i])
}
sum = sum + array[i]
}
return sum
}
console.log(countArray(array));but this does not work, anybody knows why?
Firstly you need to do single for incoming nested array.
You can use flat() method.
var nestedArray = [0, 1, 2, [3, 4]];
var flatArray = nestedArray.flat(Infinity); // [0,1,2,3,4];
Array.prototype.reduce can be used to iterate through the array,
adding the current element value to the sum of the previous element values
var totalSum = flatArray.reduce(function (accumulator, a) {
return accumulator + a;
}, 0)
So,
const array = [1, [2, [3,4]], [5,6], 7];
var countArray = function(array) {
var flatArray = array.flat(Infinity);
var totalSum = flatArray.reduce(function (accumulator, a) {
return accumulator + a;
}, 0)
return totalSum;
}
console.log(countArray(array))Two solutions. First is simply to modify these lines:
if (Array.isArray(array[i])) {
countArray(array[i])
}
sum= sum + array[i]
to these:
if (Array.isArray(array[i])) {
sum += countArray(array[i])
} else {
sum += array[i]
}
or this:
sum += Array.isArray(array[i]) ? countArray(array[i]) : array[i]
Second solution:
const array = [1, [2, [3,4]], [5,6], 7]
countArray = array => array.flat(Infinity).reduce( (a, c) => a + c, 0 );
console.log(countArray(array))The second solution depends on Array.prototype.flat, which is fairly (ECMA 2019) recent so support may not be 100%. There are other options, pretty good list here
To spare you the effort of recursion here's a simple trick.
Ordinarily, on its own, flat will only flatten a series of nested arrays one level deep. If you supply Infinity as an argument you can flatten nested arrays n-level deep, and then you can reduce over those elements to get the sum.
const array = [1, [2, [3,4]], [5,6, [3, [23, [1, 2, [12]]]]], 7];
function countArray(arr) {
return arr
.flat(Infinity)
.reduce((acc, c) => acc + c, 0);
}
console.log(countArray(array));