JavaScript Date getDay() Method

What You’ll Learn

getDay() returns the day of the week as an integer from 0 (Sunday) to 6 (Saturday) in local time. This guide covers syntax, five examples, weekday name helpers, comparisons with similar methods, and real scheduling patterns.

Introduction

Scheduling apps, store hours, and “Happy Friday” banners all need to know which weekday a Date falls on. The getDay() method extracts that weekday as a small integer using the user’s local timezone.

If you need the calendar date number instead (1–31), use getDate(). For UTC weekday logic, see getUTCDay().

Understanding the getDay() Method

Date.prototype.getDay() is a zero-argument instance method. It never mutates the original Date—it only reads the weekday component according to local time rules.

The return value is a number, not a string. Most apps map that number to a label (“Monday”) with a helper function or with toLocaleDateString({ weekday: "long" }) for locale-aware output.

📝 Syntax

dateObj.getDay()

Parameters

• None.

Return value

• Integer 0–6 for a valid date in local time (0 = Sunday, 6 = Saturday).
• NaN if dateObj is an invalid Date.

Weekday index table

• 0 — Sunday
• 1 — Monday
• 2 — Tuesday
• 3 — Wednesday
• 4 — Thursday
• 5 — Friday
• 6 — Saturday

Examples Gallery

Open DevTools Console (F12) or use Try-it links. Fixed dates use new Date(year, monthIndex, day) to avoid string parsing surprises.

const feb26 = new Date(2024, 1, 26);
const dayOfWeek = feb26.getDay();

console.log(dayOfWeek); // 1 (Monday)

1

const WEEKDAYS = [
  "Sunday", "Monday", "Tuesday", "Wednesday",
  "Thursday", "Friday", "Saturday"
];

function getDayName(dayIndex) {
  return WEEKDAYS[dayIndex];
}

const today = new Date(2024, 1, 26);
console.log("Today is a " + getDayName(today.getDay()) + ".");
// Today is a Monday.

Today is a Monday.

function safeGetDay(date) {
  if (!(date instanceof Date) || Number.isNaN(date.getTime())) {
    return null;
  }
  return date.getDay();
}

console.log(safeGetDay(new Date()));              // e.g. 5
console.log(safeGetDay(new Date("not-a-date")));  // null

5
null

function welcomeMessage() {
  const dayOfWeek = new Date().getDay();

  if (dayOfWeek === 1 || dayOfWeek === 5) {
    return "Happy coding day!";
  }
  return "Enjoy your day!";
}

console.log(welcomeMessage());

Happy coding day!
// or: Enjoy your day!

function scheduleMeeting() {
  const dayOfWeek = new Date().getDay();

  if (dayOfWeek === 2 || dayOfWeek === 4) {
    console.log("Meeting scheduled for today!");
  } else {
    console.log("No meeting today.");
  }
}

scheduleMeeting();

Meeting scheduled for today!
// or: No meeting today.

🚀 Common Use Cases

• Store hours — open/closed banners based on weekday.
• Weekend pricing — different rates when getDay() is 0 or 6.
• Recurring events — “every Tuesday” meeting logic.
• Dashboard labels — “Happy Friday” when index is 5.
• Form validation — disallow submissions on Sundays.
• Analytics buckets — group traffic by weekday index.

📝 Notes

• getDay() is local; use getUTCDay() when you standardize on UTC.
• Do not confuse with getDate() (day-of-month 1–31).
• Invalid dates propagate NaN—validate first.
• Sunday is 0 by spec; some locales start weeks on Monday in UI only.
• For display strings, prefer locale formatters over hard-coded English arrays.
• Near midnight, local weekday can differ from UTC weekday on the same instant.

💡 Best Practices