Tell us what’s happening:
tests are not passing for recursive solution although the result is exactly the same, array of squares of 1-9 which is logical because they have 3 dividors (1, sqrt and themselves) and everything else is separetad into two other numbers (and 2 more factors don’t change the door situation)

Your code so far

var arr = [];
for (let i = 1; i <= 100; i++) {arr.push(i);}
function getFinalOpenedDoors(numDoors, iter = 2) {
if (iter == 101) {return arr.filter(Boolean);}
else {
for (let i = 0; i < arr.length; i++) {
if ((i+1) % iter === 0) {
if (arr[i] !== false) arr[i] = false;
else arr[i] = i+1;
}}
return getFinalOpenedDoors(numDoors, iter+1);
}}
console.log(getFinalOpenedDoors(100))
function getFinalOpenedDoors2(numDoors) {
var arr = [];
for (let i = 1; i <= numDoors; i++) {arr.push(i);}
for (let i = 2; i <= numDoors; i++) {
for (let j = 0; j < arr.length; j++) {
if ((j+1) % i == 0 && arr[j] != false) arr[j] = false
else if ((j+1) % i === 0 && arr[j] == false) arr[j] = j + 1;
}}
return arr.filter(Boolean)
}
console.log(getFinalOpenedDoors2(100))

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.183 Safari/537.36.

Your code contains global variables that are changed each time the function is run. This means that after each test completes, subsequent tests start with the previous value. To fix this, make sure your function doesn’t change any global variables, and declare/assign variables within the function if they need to be changed.

Example:

var myGlobal = [1];
function returnGlobal(arg) {
myGlobal.push(arg);
return myGlobal;
} // unreliable - array gets longer each time the function is run
function returnLocal(arg) {
var myLocal = [1];
myLocal.push(arg);
return myLocal;
} // reliable - always returns an array of length 2

so you suggest me to put arr in the recursive function (at least i think) but will it reset it every time it is run or make the execution time much longer?