June and July 2021 are the same

[jmcolet]

June and July 2021 are the same

[rodevasia]

looks like the nextDays becomes zero in case of July. You just want to put a condition to solve it.

if (nextDays > 0) {
for (let j = 1; j <= nextDays; j++) {
days += <div class="next-date">${j}</div>;
monthDays.innerHTML = days;
}
}
else {
monthDays.innerHTML = days; }