Date.prototype.getDay() returns the day of the week as an integer 0–6 in local time, where 0 is Sunday and 6 is Saturday. It is read-only and does not change the Date.
date.getDay()
0 = Sunday
1 = Monday
2 = Tuesday
3 = Wednesday
4 = Thursday
5 = Friday
6 = Saturday
→ NaN if the Date is invalid
getDay() → weekday index
getDate() → day of month (1–31)Call date.getDay. Start with this line.
date.getDay()| Call | What it does |
|---|---|
date.getDay() | Primary signature. |
date.getDay(...) | Call with the arguments your case needs. |
Built into JavaScript. Call getDay(...) on a Date instance — no import required.
date.getDay()| Parameter | Description |
|---|---|
| Name mapping | Optional. Array index or Intl for display labels |
| Return Value | Description |
|---|---|
| * | The value returned by date.getDay(). |
Call getDay() on a fixed local date (month index is zero-based).
const birthday = new Date(1975, 7, 19); // Aug 19, 1975
console.log(birthday.getDay()); // 2 (Tuesday)new Date(1975, 7, 19) is August 19, 1975 (month index 7).getDay() returns 2 — Tuesday in the 0–6 scale.0 = Sunday, so Tuesday lands at 2.Date is unchanged; getDay only reads.Use the return value as an index into a names array (common teaching pattern).
const dayNames = [
"Sunday", "Monday", "Tuesday", "Wednesday",
"Thursday", "Friday", "Saturday"
];
const xmas = new Date(1995, 11, 25); // Dec 25, 1995
const index = xmas.getDay();
console.log(index); // 1
console.log(dayNames[index]); // "Monday"0 must be Sunday to match getDay().getDay() is 1.dayNames[1] → "Monday".Intl.DateTimeFormat with { weekday: "long" } instead of a hard-coded English array.Treat Sunday (0) and Saturday (6) as the weekend.
function isWeekend(date) {
const day = date.getDay();
return day === 0 || day === 6;
}
console.log(isWeekend(new Date(2026, 0, 3))); // true (Sat)
console.log(isWeekend(new Date(2026, 0, 5))); // false (Mon)getDay() gives 0–6.0) or Saturday (6).true.false.Date.prototype.getDay() has been in JavaScript since ES1. It is Baseline and works in every modern browser and Node.js — no polyfill needed.
Supported everywhere Date exists: Chrome, Firefox, Safari, Edge, Internet Explorer, and all Node.js versions.
Bottom line: Safe to use in any environment. Focus on Sunday-first indexing and local vs UTC correctness. See also the MDN getDay() reference.
Learn how to read the four-digit year from a Date in local time.
11 people found this page helpful