How to convert my output as a linked list

Question

var addTwoNumbers = function(l1, l2) {
let strL1="";
for(let i=l1.length-1;i>=0;i--){
strL1+=l1[i];
}
let numL1=Number(strL1);

let strL2="";
for(let i=l2.length-1;i>=0;i--){
strL2+=l2[i];
}
let numL2=Number(strL2);

let result = (numL1 + numL2).toString();

let rev=[];
for(let i=result.length-1;i>=0;i--){
rev.push(result[i]);
}
console.log(rev.map(Number));//How to convert it to linked list
};

addTwoNumbers([9,9,9,9,9,9,9], [9,9,9,9]);

Answer 1

This is some tutorial about linked list in java script
https://www.google.com/amp/s/www.freecodecamp.org/news/implementing-a-linked-list-in-javascript/amp/

Answer 2

It's in array format

Answer 3

How you output need to look like?

Your output is [8, 9, 9, 9, 0, 0, 0, 1], but sololearn compile it as 8,9,9,9,0,0,0,1
If you test your code somewere else you will see normal array