I am getting NaN when looping over an array inside an if statement. How can I sum up an array of even and odd nums?

Question

I am trying to extra even and odd numbers of number(10), however when I try to sum the m5 which is an array of even numbers, I get the NaN. How can I add the sum of 5 and 3 in my loop?

    let number = 10;
let array1 = new Array();
let m5 = new Array();
let m3 = new Array();

let sum5 = 0;
let sum3 = 0;
let arraySum = 0;


for (let i=0; i <= number; i++) {
    array1.push(i)

    if (array1[i] % 5 === 0 && array1[i] < number) {
        m5.push(i); // 0, 5
        sum5 += m5[i];
        console.log(sum5); //Return NaN
    }

    if (array1[i] % 3 === 0) {
        m3.push(i)

    }
    arraySum += array1[i];
}

Answer 1

Your problem is an out of bounds issue. You are trying to push the value of i to the m5 array, but the index where this value is put is different. You need to track the index and the values separately. I created a variable j to track the index for the m5 array. You will need to do the same for array m3.

let number = 10;
let array1 = new Array();
let m5 = new Array();
let m3 = new Array();

let sum5 = 0;
let sum3 = 0;
let arraySum = 0;


for (let i=0, j=0; i <= number; i++) {
    array1.push(i)

    if (array1[i] % 5 === 0 && array1[i] < number) {
        m5.push(i); // 0, 5
        sum5 += m5[j++];
        console.log(sum5); //Return the sum correctly
    }

    if (array1[i] % 3 === 0) {
        m3.push(i)

    }
    arraySum += array1[i];
}