Add date utility functions (#16)

Resolves #9

Author: drebrez

.eslintrc.cjs

@@ -79,7 +79,7 @@ module.exports = {
           "FunctionDeclaration",
           "FunctionExpression",
           "MethodDefinition",
-          "Property",
+          "PropertyDefinition",
           "TSDeclareFunction",
           "TSEnumDeclaration",
           "TSInterfaceDeclaration",

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+- added `dateIsValid`, `dateIsLastDayOfMonth` and `dateDifferenceInDays` utility functions
+
 ## [0.1.1] - 2023-08-04
 
 ### Fixed

package.json

@@ -42,7 +42,9 @@
     "start-yalc": "yarn nodemon --watch dist -x \"yarn yalc push\"",
     "storybook": "start-storybook -p 6006"
   },
-  "dependencies": {},
+  "dependencies": {
+    "date-fns": "^2.30.0"
+  },
   "devDependencies": {
     "@babel/core": "^7.21.8",
     "@popperjs/core": "^2.11.7",

src/index.ts

@@ -1 +1,2 @@
+export * from "./lib/date";
 export * from "./lib/enum";

src/lib/date.spec.ts

@@ -0,0 +1,44 @@
+import { dateIsValid, dateIsLastDayOfMonth, dateDifferenceInDays } from "./date";
+
+describe("date tests", () => {
+  test.each([
+    // Valid dates
+    [new Date(), true],
+    [new Date(new Date()), true],
+    [new Date("2014-03-15"), true],
+    [new Date(2014, 3, 15), true],
+    [new Date(42), true],
+
+    // Invalid dates
+    [new Date(Number.MAX_VALUE), false],
+    [new Date(Number.NaN), false],
+    [new Date("2014-03-36"), false],
+    [null as unknown as Date, false],
+    [undefined as unknown as Date, false],
+    [42 as unknown as Date, false],
+    ["2014-03-15" as unknown as Date, false],
+    [{ year: 2014, month: 2, day: 15 } as unknown as Date, false],
+  ])("dateIsValid", (date, expected) => {
+    expect(dateIsValid(date)).toBe(expected);
+  });
+
+  test.each([
+    [new Date(2014, 12, 31), true],
+    [new Date(2014, 12, 30), false],
+    [new Date(2015, 1, 1), false],
+  ])("dateIsLastDayOfMonth", (date, expected) => {
+    expect(dateIsLastDayOfMonth(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],
+    [new Date(2014, 3, 16), new Date(2014, 3, 15), 1],
+    [new Date(2014, 3, 15, 0, 0), new Date(2014, 3, 15, 23, 59), 0],
+    [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],
+  ])("dateDifferenceInDays", (dateFrom, dateTo, expected) => {
+    expect(dateDifferenceInDays(dateFrom, dateTo)).toBe(expected);
+  });
+});

src/lib/date.ts

@@ -0,0 +1,30 @@
+import { isDate, isValid, isLastDayOfMonth, differenceInCalendarDays } from "date-fns";
+
+/**
+ * Check whether the date is valid
+ * @param date The date
+ * @returns A boolean indicating whether the date is valid
+ */
+export function dateIsValid(date: Date): boolean {
+  return isDate(date) && isValid(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);
+}
+
+/**
+ * Calculate the difference in days between two dates
+ * The order is not relevant hence the result is always positive
+ * @param from The start date
+ * @param to The end date
+ * @returns The difference in days between two dates
+ */
+export function dateDifferenceInDays(from: Date, to: Date): number {
+  return Math.abs(differenceInCalendarDays(from, to));
+}

yarn.lock

@@ -2281,7 +2281,7 @@ data-uri-to-buffer@^5.0.1:
   resolved "https://registry.yarnpkg.com/data-uri-to-buffer/-/data-uri-to-buffer-5.0.1.tgz#db89a9e279c2ffe74f50637a59a32fb23b3e4d7c"
   integrity sha512-a9l6T1qqDogvvnw0nKlfZzqsyikEBZBClF39V3TFoKhDtGBqHu2HkuomJc02j5zft8zrUaXEuoicLeW54RkzPg==
 
-date-fns@^2.29.3:
+date-fns@^2.29.3, date-fns@^2.30.0:
   version "2.30.0"
   resolved "https://registry.yarnpkg.com/date-fns/-/date-fns-2.30.0.tgz#f367e644839ff57894ec6ac480de40cae4b0f4d0"
   integrity sha512-fnULvOpxnC5/Vg3NCiWelDsLiUc9bRwAPs/+LfTLNvetFCtCTN+yQz15C/fs4AwX1R9K5GLtLfn8QW+dWisaAw==