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Checker Methods

isBefore()​

Signature​

isBefore(other: ChronosInput, unit?: TimeUnit, weekStartsOn?: Enumerate<7>): boolean

Parameters​

  • other: The date to compare against (can be string, Date, or Chronos instance)
  • unit: (Optional) The granularity for comparison ('year', 'month', 'week', 'day', 'hour', 'minute', 'second')
  • weekStartsOn: (Optional) Which day (0-6, Sunday-Saturday) to consider as the start of the week (default: 0/Sunday)

Return Type​

boolean - Returns true if the current Chronos date is before the comparison date

Example​

// Compare entire dates
new Chronos('2025-01-01').isBefore('2025-02-01'); // true

// Compare just the months
new Chronos('2025-01-15').isBefore('2025-02-01', 'month'); // true

isAfter()​

Signature​

isAfter(other: ChronosInput, unit?: TimeUnit, weekStartsOn?: Enumerate<7>): boolean

Parameters​

  • other: The date to compare against (can be string, Date, or Chronos instance)
  • unit: (Optional) The granularity for comparison ('year', 'month', 'week', 'day', 'hour', 'minute', 'second')
  • weekStartsOn: (Optional) Which day (0-6, Sunday-Saturday) to consider as the start of the week (default: 0/Sunday)

Return Type​

boolean - Returns true if the current date occurs after the comparison date

Example​

// Basic date comparison
new Chronos('2025-02-01').isAfter('2025-01-01'); // true

// Compare specific units
new Chronos('2025-01-15T12:00:00').isAfter('2025-01-15T10:00:00', 'hour'); // true

isSame()​

Signature​

isSame(other: ChronosInput, unit?: TimeUnit, weekStartsOn?: Enumerate<7>): boolean

Parameters​

  • other: The date to compare against (can be string, Date, or Chronos instance)
  • unit: (Optional) The granularity for comparison ('year', 'month', 'week', 'day', 'hour', 'minute', 'second')
  • weekStartsOn: (Optional) Which day (0-6, Sunday-Saturday) to consider as the start of the week (default: 0/Sunday)

Return Type​

boolean - Returns true if dates match at the specified precision level

Example​

// Exact match
new Chronos('2025-01-15').isSame('2025-01-15'); // true

// Same month but different days
new Chronos('2025-01-15').isSame('2025-01-20', 'month'); // true
new Chronos('2025-01-15').isSame('2025-01-20', 'day'); // false

isSameOrBefore()​

Signature​

isSameOrBefore(other: ChronosInput, unit: TimeUnit, weekStartsOn?: Enumerate<7>): boolean

Parameters​

  • other: The date to compare against (can be string, Date, or Chronos instance)
  • unit: The granularity for comparison ('year', 'month', 'week', 'day', 'hour', 'minute', 'second')
  • weekStartsOn: (Optional) Which day (0-6, Sunday-Saturday) to consider as the start of the week (default: 0/Sunday)

Return Type​

boolean - Returns true if the current Chronos date is either:

  • Exactly equal to the comparison date at the specified unit level, OR
  • Occurs before the comparison date at the specified unit level

Example​

// Same month
new Chronos('2025-01-15').isSameOrBefore('2025-01-20', 'month'); // true

// Earlier month
new Chronos('2025-01-15').isSameOrBefore('2025-02-01', 'month'); // true

// Later month
new Chronos('2025-02-15').isSameOrBefore('2025-01-20', 'month'); // false

isSameOrAfter()​

Signature​

isSameOrAfter(other: ChronosInput, unit: TimeUnit, weekStartsOn?: Enumerate<7>): boolean

Parameters​

  • other: The date to compare against (can be string, Date, or Chronos instance)
  • unit: The granularity for comparison ('year', 'month', 'week', 'day', 'hour', 'minute', 'second')
  • weekStartsOn: (Optional) Which day (0-6, Sunday-Saturday) to consider as the start of the week (default: 0/Sunday)

Return Type​

boolean - Returns true if the current Chronos date is either:

  • Exactly equal to the comparison date at the specified unit level, OR
  • Occurs after the comparison date at the specified unit level

Example​

// Same month
new Chronos('2025-01-20').isSameOrAfter('2025-01-15', 'month'); // true

// Later month
new Chronos('2025-02-01').isSameOrAfter('2025-01-15', 'month'); // true

// Earlier month
new Chronos('2025-01-01').isSameOrAfter('2025-02-15', 'month'); // false

isBetween()​

Signature​

isBetween(
  start: ChronosInput,
  end: ChronosInput,
  inclusive?: '[]' | '[)' | '(]' | '()'
): boolean

Parameters​

  • start: Start of date range
  • end: End of date range
  • inclusive: (Optional) Range boundary inclusion:
    • []: Include both start and end
    • [) Include start, exclude end
    • (]: Exclude start, include end
    • (): Exclude both boundaries (default)

Return Type​

boolean - Returns true if the date falls within the specified range

Example​

const date = new Chronos('2025-01-15');

// Default exclusive end
date.isBetween('2025-01-01', '2025-01-31'); // true

// Inclusive range
date.isBetween('2025-01-15', '2025-01-20', '[]'); // true

// Exclusive range
date.isBetween('2025-01-01', '2025-01-15', '()'); // false

isEqual()​

Signature​

isEqual(other: ChronosInput): boolean

Parameters​

  • other: The date to compare against (can be string, Date, or Chronos instance)

Return Type​

boolean - Returns true if the current Chronos date is exactly equal to the comparison date (including time components)

Example​

// Exact timestamp match
const date1 = new Chronos('2025-01-01T12:00:00');
const date2 = new Chronos('2025-01-01T12:00:00');
date1.isEqual(date2); // true

// Different time components
new Chronos('2025-01-01T12:00:00').isEqual('2025-01-01T12:00:01'); // false

isEqualOrBefore()​

Signature​

isEqualOrBefore(other: ChronosInput): boolean

Parameters​

  • other: The date to compare against (can be string, Date, or Chronos instance)

Return Type​

boolean - Returns true if the current Chronos date is either:

  • Exactly equal to the comparison date, OR
  • Occurs before the comparison date

Example​

// Equal dates
new Chronos('2025-01-15').isEqualOrBefore('2025-01-15'); // true

// Earlier date
new Chronos('2025-01-10').isEqualOrBefore('2025-01-15'); // true

// Later date
new Chronos('2025-01-20').isEqualOrBefore('2025-01-15'); // false

isEqualOrAfter()​

Signature​

isEqualOrAfter(other: ChronosInput): boolean

Parameters​

  • other: The date to compare against (can be string, Date, or Chronos instance)

Return Type​

boolean - Returns true if the current Chronos date is either:

  • Exactly equal to the comparison date, OR
  • Occurs after the comparison date

Example​

// Equal dates
new Chronos('2025-01-15').isEqualOrAfter('2025-01-15'); // true

// Later date
new Chronos('2025-01-20').isEqualOrAfter('2025-01-15'); // true

// Earlier date
new Chronos('2025-01-10').isEqualOrAfter('2025-01-15'); // false

isToday()​

Note

This method is provided by relativeTimePlugin. You must register it using Chronos.use(relativeTimePlugin) before calling .isToday(). Once registered, all Chronos instances will have access to the .isToday() method.

Signature​

isToday(): boolean

Return Type​

boolean - Whether date is today

Example​

import { Chronos } from 'nhb-toolbox';
import { relativeTimePlugin } from 'nhb-toolbox/plugins/relativeTimePlugin';

Chronos.use(relativeTimePlugin);

new Chronos().isToday(); // true

isTomorrow()​

Note

This method is provided by relativeTimePlugin. You must register it using Chronos.use(relativeTimePlugin) before calling .isTomorrow(). Once registered, all Chronos instances will have access to the .isTomorrow() method.

Signature​

isTomorrow(): boolean

Return Type​

boolean - Whether date is tomorrow

Example​

import { Chronos } from 'nhb-toolbox';
import { relativeTimePlugin } from 'nhb-toolbox/plugins/relativeTimePlugin';

Chronos.use(relativeTimePlugin);

new Chronos().add(1, 'day').isTomorrow(); // true

isYesterday()​

Note

This method is provided by relativeTimePlugin. You must register it using Chronos.use(relativeTimePlugin) before calling .isYesterday(). Once registered, all Chronos instances will have access to the .isYesterday() method.

Signature​

isYesterday(): boolean

Return Type​

boolean - Whether date is yesterday

Example​

import { Chronos } from 'nhb-toolbox';
import { relativeTimePlugin } from 'nhb-toolbox/plugins/relativeTimePlugin';

Chronos.use(relativeTimePlugin);

new Chronos().subtract(1, 'day').isYesterday(); // true

isWeekend()​

Note

This method is provided by businessPlugin. You must register it using Chronos.use(businessPlugin) before calling .isWeekend(). Once registered, all Chronos instances will have access to the .isWeekend() method.

Signatures​

isWeekend(weekStartsOn?: Enumerate<7>, weekendLength?: NumberRange<1, 4>): boolean;

isWeekend(weekendDays: RangeTuple<Enumerate<7>, 1, 4>): boolean;

Parameters​

  • By default (weekStartsOn = 0, weekendLength = 2), Saturday (6) and Friday (5) are considered weekend.
    • weekStartsOn sets the start of the week for calculating weekend days.
    • weekendLength sets how many days at the end of the week are treated as weekend.
    • weekendDays is used directly as the weekend days instead of calculating from weekStartsOn + weekendLength.

Return Type​

boolean - Whether weekend (true) or not (false)

Example​

import { Chronos } from 'nhb-toolbox';
import { businessPlugin } from 'nhb-toolbox/plugins/businessPlugin';

Chronos.use(businessPlugin);

new Chronos('2025-01-11').isWeekend(); // true (Saturday)

// Default: Saturday & Friday are weekend
new Chronos().isWeekend();

// Custom week start (Monday) with 2-day weekend (Saturday & Sunday)
new Chronos().isWeekend(1, 2);

// Custom 3-day weekend (Friday–Sunday)
new Chronos().isWeekend(1, 3);

// Fully custom weekend days (Sunday, Friday, Saturday)
new Chronos().isWeekend([0, 5, 6]);

isWorkday()​

Note

This method is provided by businessPlugin. You must register it using Chronos.use(businessPlugin) before calling .isWorkday(). Once registered, all Chronos instances will have access to the .isWorkday() method.

Signatures​

isWorkday(weekStartsOn?: Enumerate<7>, weekendLength?: NumberRange<1, 4>): boolean;

isWorkday(weekendDays: RangeTuple<Enumerate<7>, 1, 4>): boolean;

Parameters​

  • By default (weekStartsOn = 0, weekendLength = 2), Saturday (6) and Friday (5) are considered weekend.
    • weekStartsOn sets the start of the week for calculating weekend days.
    • weekendLength sets how many days at the end of the week are treated as weekend.
    • weekendDays is used directly as the weekend days instead of calculating from weekStartsOn + weekendLength.

Return Type​

boolean - Whether workday (true) or not (false)

Example​

import { Chronos } from 'nhb-toolbox';
import { businessPlugin } from 'nhb-toolbox/plugins/businessPlugin';

Chronos.use(businessPlugin);

new Chronos('2025-01-16').isWorkday(); // true (Thursday)
Hint

This method internally uses isWeekend method.

isBusinessHour()​

Note

This method is provided by businessPlugin. You must register it using Chronos.use(businessPlugin) before calling .isBusinessHour(). Once registered, all Chronos instances will have access to the .isBusinessHour() method.

Signatures​

isBusinessHour(options?: BusinessOptionsBasic): boolean;

isBusinessHour(options?: BusinessOptionsWeekends): boolean;

Parameters​

  • options: Options to configure business hour

Options Type Definitions​

interface $BusinessHourBaseOptions {
 /** - Optional starting hour of business time (0–23). Defaults to `9` (9 AM). */
 businessStartHour?: Enumerate<24>;
 /** - Optional ending hour of business time (0–23). Defaults to `17` (5 PM). */
 businessEndHour?: Enumerate<24>;
}

/** Options for configuring business hour with `weekStartsOn` and `weekendLength` */
interface BusinessOptionsBasic extends $BusinessHourBaseOptions {
 /** - Optional day the week starts on (0–6). Default is `0` (Sunday). */
 weekStartsOn?: Enumerate<7> | undefined;
 /** - Optional weekend length (1-4). Default is `2`.*/
 weekendLength?: NumberRange<1, 4> | undefined;
}

/** Options for configuring business hour with `weekendDays` tuple */
interface BusinessOptionsWeekends extends $BusinessHourBaseOptions {
 /** - Tuple of indices (0-6) of weekend days. Can pass only 1-4 elements. Default is `undefined`. */
 weekendDays?: RangeTuple<Enumerate<7>, 1, 4> | undefined;
}

Return Type​

boolean - Whether business hour (true) or not (false)

Example​

import { Chronos } from 'nhb-toolbox';
import { businessPlugin } from 'nhb-toolbox/plugins/businessPlugin';

Chronos.use(businessPlugin);

new Chronos('2025-01-16T10:00:00').isBusinessHour(); // true

new Chronos().isBusinessHour({ weekendDays: [0, 2, 4] });

// Or

new Chronos().isBusinessHour({ weekendLength: 3 });

:::

Note

Weekends are determined by weekStartsOn and weekendLength or weekdays array if provided using the isWeekend method.

isPalindromeDate()​

Note

This method is provided by palindromePlugin. You must register it using Chronos.use(palindromePlugin) before calling .isPalindromeDate(). Once registered, all Chronos instances will have access to the .isPalindromeDate() method.

Signature​

isPalindromeDate(shortYear?: boolean): boolean

Parameters​

  • shortYear: Use 2-digit year (default: false)

Return Type​

boolean - Whether palindrome date

Example​

import { palindromePlugin } from 'nhb-toolbox/plugins/palindromePlugin';

Chronos.use(palindromePlugin);

new Chronos('2020-02-02').isPalindromeDate(); // true

isDST()​

Signature​

isDST(): boolean

Return Type​

boolean - Returns true if the date is in Daylight Saving Time for the current timezone

Note
  • Detection is based on the system's timezone settings
  • Only accurate for timezones that observe DST

Example​

// Northern hemisphere summer
new Chronos('2025-07-01').isDST(); // true

// Northern hemisphere winter
new Chronos('2025-01-01').isDST(); // false

isFirstDayOfMonth()​

Signature​

isFirstDayOfMonth(): boolean

Return Type​

boolean - Whether first day

Example​

new Chronos('2025-01-01').isFirstDayOfMonth(); // true

isLastDayOfMonth()​

Signature​

isLastDayOfMonth(): boolean

Return Type​

boolean - Whether last day

Example​

new Chronos('2025-01-31').isLastDayOfMonth(); // true

isLeapYear()​

info

  • A year is a leap year if it is divisible by 4.

  • However, years divisible by 100 are not leap years unless they are also divisible by 400.

  • For example:

    • 2000, 2400 → leap years ✅
    • 1900, 2100 → not leap years ❌

Signature​

isLeapYear(year?: number): boolean

Parameters​

year (optional): The year to check. If omitted, the method uses the year from the current Chronos instance.

Return Value​

boolean — Returns true if the year is a leap year, otherwise false.

Example Usage​

new Chronos().isLeapYear(2024); // true
new Chronos('2025-05-29').isLeapYear(); // false