let numA = "1234567890",numB = "123456789";
let numAArray = numA.split("").map((item) =>parseInt(item)).reverse();
let numBArray = numB.split("").map((item) =>parseInt(item)).reverse();
let sum = [].fill(0,0,(numA.length >= numB.length ? numA.length : numB.length) + 1);
for (let i = 0; i < numAArray.length; i++) {
sum[i] = numAArray[i];
}
let up = 0;
for (let i = 0; i < numBArray.length; i++) {
sum[i] = sum[i] + numBArray[i] + up;
if (sum[i] > 9) {
sum[i] = sum[i] % 10;
up = 1;
} else {
up = 0;
}
}
if (sum[sum.length - 1] == 0) {sum.pop()}
let result = sum.reverse().join("");
console.log(Number(numA) + Number(numB));
console.log(result);
