isSameDay.md

isSameDay()

Checks if two Date objects represent the same calendar day, regardless of time.

Syntax

isSameDay(date1, date2)

Parameters

Parameter	Type	Required	Description
date1	Date	Yes	The first Date object to compare
date2	Date	Yes	The second Date object to compare

Returns

boolean - Returns true if both dates are on the same calendar day, false otherwise

Basic Examples

Comparing Calendar Days

import { isSameDay } from 'date-and-time';

const morning = new Date(2024, 7, 15, 9, 30, 0);   // August 15, 2024 09:30:00
const evening = new Date(2024, 7, 15, 18, 45, 30);  // August 15, 2024 18:45:30
const nextDay = new Date(2024, 7, 16, 9, 30, 0);    // August 16, 2024 09:30:00

console.log(isSameDay(morning, evening)); // true (same day, different times)
console.log(isSameDay(morning, nextDay)); // false (different days)

Ignoring Time Components

const startOfDay = new Date(2024, 7, 15, 0, 0, 0, 0);     // August 15, 2024 00:00:00.000
const endOfDay = new Date(2024, 7, 15, 23, 59, 59, 999);  // August 15, 2024 23:59:59.999

console.log(isSameDay(startOfDay, endOfDay)); // true

// Even milliseconds don't matter for day comparison
const precise1 = new Date(2024, 7, 15, 12, 30, 45, 123);
const precise2 = new Date(2024, 7, 15, 12, 30, 45, 456);

console.log(isSameDay(precise1, precise2)); // true