Add more date utility functions

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+- added `dateIsFirstDayOfMonth`, `dateIsLeapYear`, `dateIsWeekend` and `getNextBusinessDate` utility functions
+
 ## [0.5.0] - 2024-03-15
 
 ### Added

src/lib/date.spec.ts

@@ -1,4 +1,12 @@
-import { dateIsValid, dateIsLastDayOfMonth, dateDifferenceInDays } from "./date";
+import {
+  dateIsValid,
+  dateIsFirstDayOfMonth,
+  dateIsLastDayOfMonth,
+  dateIsLeapYear,
+  dateIsWeekend,
+  dateDifferenceInDays,
+  getNextBusinessDate,
+} from "./date";
 
 describe("date tests", () => {
   test.each([
@@ -22,6 +30,14 @@ describe("date tests", () => {
     expect(dateIsValid(date)).toBe(expected);
   });
 
+  test.each([
+    [new Date(2015, 0, 1), true],
+    [new Date(2015, 1, 1), true],
+    [new Date(2015, 12, 30), false],
+  ])("dateIsFirstDayOfMonth", (date, expected) => {
+    expect(dateIsFirstDayOfMonth(date)).toBe(expected);
+  });
+
   test.each([
     [new Date(2014, 12, 31), true],
     [new Date(2014, 12, 30), false],
@@ -30,6 +46,34 @@ describe("date tests", () => {
     expect(dateIsLastDayOfMonth(date)).toBe(expected);
   });
 
+  test.each([
+    [new Date(2000, 0, 1), true],
+    [new Date(2004, 0, 1), true],
+    [new Date(2008, 0, 1), true],
+    [new Date(2009, 0, 1), false],
+    [new Date(2010, 0, 1), false],
+    [new Date(1900, 0, 1), false],
+    [new Date(2100, 0, 1), false],
+    [new Date(2200, 0, 1), false],
+    [new Date(2300, 0, 1), false],
+    [new Date(2400, 0, 1), true],
+  ])("dateIsLeapYear", (date, expected) => {
+    expect(dateIsLeapYear(date)).toBe(expected);
+  });
+
+  test.each([
+    [new Date(2024, 0, 1), false], // Monday
+    [new Date(2024, 0, 2), false], // Tuesday
+    [new Date(2024, 0, 3), false], // Wednesday
+    [new Date(2024, 0, 4), false], // Thursday
+    [new Date(2024, 0, 5), false], // Friday
+    [new Date(2024, 0, 6), true], // Saturday
+    [new Date(2024, 0, 7), true], // Sunday
+    [new Date(2024, 0, 8), false], // Monday
+  ])("dateIsWeekend", (date, expected) => {
+    expect(dateIsWeekend(date)).toBe(expected);
+  });
+
   test.each([
     [new Date(2014, 3, 15), new Date(2014, 3, 15), 0],
     [new Date(2014, 3, 15), new Date(2014, 3, 16), 1],
@@ -38,7 +82,30 @@ describe("date tests", () => {
     [new Date(2014, 3, 15, 23, 59), new Date(2014, 3, 16, 0, 0), 1],
     [null as unknown as Date, new Date(), Number.NaN],
     [new Date(), null as unknown as Date, Number.NaN],
+    [undefined as unknown as Date, new Date(), Number.NaN],
+    [new Date(), undefined as unknown as Date, Number.NaN],
+    [42 as unknown as Date, new Date(), Number.NaN],
+    [new Date(), 42 as unknown as Date, Number.NaN],
+    ["2014-03-15" as unknown as Date, new Date(), Number.NaN],
+    [new Date(), "2014-03-15" as unknown as Date, Number.NaN],
   ])("dateDifferenceInDays", (dateFrom, dateTo, expected) => {
     expect(dateDifferenceInDays(dateFrom, dateTo)).toBe(expected);
   });
+
+  test.each([
+    [new Date(2024, 0, 1), new Date(2024, 0, 2)],
+    [new Date(2024, 0, 2), new Date(2024, 0, 3)],
+    [new Date(2024, 0, 3), new Date(2024, 0, 4)],
+    [new Date(2024, 0, 4), new Date(2024, 0, 5)],
+    [new Date(2024, 0, 5), new Date(2024, 0, 8)],
+    [new Date(2024, 0, 6), new Date(2024, 0, 8)],
+    [new Date(2024, 0, 7), new Date(2024, 0, 8)],
+    [new Date(2024, 0, 8), new Date(2024, 0, 9)],
+    [null as unknown as Date, new Date(Number.NaN)],
+    [undefined as unknown as Date, new Date(Number.NaN)],
+    [42 as unknown as Date, new Date(Number.NaN)],
+    ["test" as unknown as Date, new Date(Number.NaN)],
+  ])("getNextBusinessDate", (date, expected) => {
+    expect(getNextBusinessDate(date).getDate()).toBe(expected.getDate());
+  });
 });

src/lib/date.ts

@@ -1,4 +1,13 @@
-import { isDate, isValid, isLastDayOfMonth, differenceInCalendarDays } from "date-fns";
+import {
+  isDate,
+  isValid,
+  isFirstDayOfMonth,
+  isLastDayOfMonth,
+  isLeapYear,
+  isWeekend,
+  differenceInCalendarDays,
+  addBusinessDays,
+} from "date-fns";
 
 /**
  * Check whether the date is valid
@@ -9,13 +18,40 @@ export function dateIsValid(date: Date): boolean {
   return isDate(date) && isValid(date);
 }
 
+/**
+ * Check whether the date is the first day of the month
+ * @param date The date
+ * @returns A boolean indicating whether the date is the first day of the month
+ */
+export function dateIsFirstDayOfMonth(date: Date): boolean {
+  return dateIsValid(date) && isFirstDayOfMonth(date);
+}
+
 /**
  * Check whether the date is the last day of the month
  * @param date The date
  * @returns A boolean indicating whether the date is the last day of the month
  */
 export function dateIsLastDayOfMonth(date: Date): boolean {
-  return isDate(date) && isLastDayOfMonth(date);
+  return dateIsValid(date) && isLastDayOfMonth(date);
+}
+
+/**
+ * Check whether the date is a leap year
+ * @param date The date
+ * @returns A boolean indicating whether the date is a leap year
+ */
+export function dateIsLeapYear(date: Date): boolean {
+  return dateIsValid(date) && isLeapYear(date);
+}
+
+/**
+ * Check whether the date is a weekend
+ * @param date The date
+ * @returns A boolean indicating whether the date is a weekend
+ */
+export function dateIsWeekend(date: Date): boolean {
+  return dateIsValid(date) && isWeekend(date);
 }
 
 /**
@@ -26,5 +62,14 @@ export function dateIsLastDayOfMonth(date: Date): boolean {
  * @returns The difference in days between two dates
  */
 export function dateDifferenceInDays(from: Date, to: Date): number {
-  return Math.abs(differenceInCalendarDays(from, to));
+  return dateIsValid(from) && dateIsValid(to) ? Math.abs(differenceInCalendarDays(from, to)) : Number.NaN;
+}
+
+/**
+ * Get the next business date
+ * @param date The date
+ * @returns The next business date
+ */
+export function getNextBusinessDate(date: Date): Date {
+  return dateIsValid(date) ? addBusinessDays(date, 1) : new Date(Number.NaN);
 }