getMonth()
ES1+Returns the month (0-11) in the specified date according to local time.
Syntax
date.getMonth()Return Value
A number (0-11) representing the month
Examples
const date = new Date('2024-03-15');
console.log(date.getMonth()); // 3월은 2
console.log(date.getMonth() + 1); // 실제 월📌 When to Use
Use getMonth() for month-based filtering, calendar generation, monthly reports, or any feature requiring the month component.
⚠️ Common Mistakes
Forgetting that months are 0-indexed (January = 0, December = 11). Always add 1 for display.
Using getMonth() directly in month name arrays without accounting for the 0-based index.
✅ Best Practices
Create a month names array and use getMonth() as index: months[date.getMonth()].
For user-facing month display, use toLocaleString with month option for localized names.
⚡ Performance Notes
getMonth() is a direct property access with negligible overhead. For formatted month names, consider caching locale-formatted strings if called repeatedly.
🌍 Real World Example
Monthly Activity Calendar
Group activities by month and display them with localized month names.
function groupActivitiesByMonth(activities, locale = 'ko-KR') {
const grouped = {};
activities.forEach(activity => {
const date = new Date(activity.date);
const monthKey = `${date.getFullYear()}-${date.getMonth()}`;
const monthName = date.toLocaleString(locale, { month: 'long', year: 'numeric' });
if (!grouped[monthKey]) {
grouped[monthKey] = { monthName, activities: [] };
}
grouped[monthKey].activities.push(activity);
});
return Object.values(grouped);
}
const activities = [
{ name: 'Meeting', date: '2024-03-15' },
{ name: 'Workshop', date: '2024-03-20' },
{ name: 'Conference', date: '2024-04-10' }
];
console.log(groupActivitiesByMonth(activities));
// [{ monthName: '2024년 3월', activities: [...] }, { monthName: '2024년 4월', activities: [...] }]