The first date as a Date object or timestamp (number)
The second date as a Date object or timestamp (number)
Optionalopts: { unit?: TimeUnit }Optional configuration object
Optionalunit?: TimeUnitThe unit of comparison (year, month, day, hour, minute, second, millisecond). Defaults to "millisecond"
True if date a is before or equal to date b, false otherwise or if either date is invalid
// Basic comparison (millisecond precision)
const result = isBeforeOrEqual(new Date(2025, 0, 1), new Date(2025, 0, 2));
// Returns: true
// Equality returns true
const date = new Date(2025, 0, 1);
const result2 = isBeforeOrEqual(date, date);
// Returns: true
// Compare at day granularity
const result3 = isBeforeOrEqual(
new Date(2025, 0, 1, 0, 0),
new Date(2025, 0, 1, 23, 59),
{ unit: "day" }
);
// Returns: true (same day)
// Works with timestamps
const result4 = isBeforeOrEqual(Date.now() - 1000, Date.now());
// Returns: true (1 second ago is before current time)
// Invalid dates return false
const result5 = isBeforeOrEqual(new Date("invalid"), new Date(2025, 0, 1));
// Returns: false
Check if the first date is before or equal to the second date.
This function compares two dates and returns true if the first date is chronologically before or equal to the second date. The comparison can be performed at different granularities (year, month, day, hour, minute, second, or millisecond).