feat(date): addYear, addMonth, addDate, addHours, addMinutes, addSeconds, addMilliseconds

Author: SamuelScheit

src/Date.ts

@@ -7,18 +7,48 @@ define(Date, {
 });
 
 define(Date.prototype, {
-	setTimezone: function (timezone: string) {
+	setTimezone: function (this: Date, timezone: string) {
 		return new Date(
 			this.toLocaleString("en-US", {
 				timeZone: timezone,
 			})
 		);
 	},
-	isInPast: function () {
+	isInPast: function (this: Date) {
 		const today = new Date();
 		today.setHours(0, 0, 0, 0);
 		return this < today;
 	},
+	addYear: function (this: Date, years: number, month: number = 0, date: number = 0) {
+		return this.setFullYear(this.getFullYear() + years, this.getMonth() + month, this.getDate() + date);
+	},
+	addMonth: function (this: Date, months: number, date: number = 0) {
+		return this.setMonth(this.getMonth() + months, this.getDate() + date);
+	},
+	addDate: function (this: Date, days: number) {
+		return this.setDate(this.getDate() + days);
+	},
+	addHours: function (this: Date, hours: number, minutes: number = 0, seconds: number = 0, milliseconds: number = 0) {
+		return this.setHours(
+			this.getHours() + hours,
+			this.getMinutes() + minutes,
+			this.getSeconds() + seconds,
+			this.getMilliseconds() + milliseconds
+		);
+	},
+	addMinutes: function (this: Date, minutes: number, seconds: number = 0, milliseconds: number = 0) {
+		return this.setMinutes(
+			this.getMinutes() + minutes,
+			this.getSeconds() + seconds,
+			this.getMilliseconds() + milliseconds
+		);
+	},
+	addSeconds: function (this: Date, seconds: number, milliseconds: number = 0) {
+		return this.setSeconds(this.getSeconds() + seconds, this.getMilliseconds() + milliseconds);
+	},
+	addMilliseconds: function (this: Date, milliseconds: number) {
+		return this.setMilliseconds(this.getMilliseconds() + milliseconds);
+	},
 });
 
 declare global {
@@ -27,7 +57,7 @@ declare global {
 		 * Returns the current timestamp as its representation in seconds
 		 * @returns {number} date in seconds
 		 * @example
-		 * Date.nowSeconds() // 1671621321
+		 * Date.nowSeconds()
 		 */
 		nowSeconds(): number;
 	}
@@ -51,6 +81,55 @@ declare global {
 		 * new Date("2022-12-01").isInPast() // returns: true
 		 */
 		isInPast(): boolean;
+		/**
+		 * Add a number of years to the current date
+		 * @returns {number} timestamp in milliseconds
+		 * @example
+		 * new Date().addYear(1)
+		 */
+		addYear(years: number, month?: number, date?: number): number;
+		/**
+		 * Add a number of months to the current date
+		 * @returns {number} timestamp in milliseconds
+		 * @example
+		 * new Date().addMonth(1)
+		 */
+		addMonth(months: number, date?: number): number;
+		/**
+		 * Add a number of days to the current date
+		 * @returns {number} timestamp in milliseconds
+		 * @example
+		 * new Date().addDate(1)
+		 */
+		addDate(days: number): number;
+		/**
+		 * Add a number of hours to the current date
+		 * @returns {number} timestamp in milliseconds
+		 * @example
+		 * new Date().addHours(1)
+		 */
+		addHours(hours: number, minutes?: number, seconds?: number, milliseconds?: number): number;
+		/**
+		 * Add a number of minutes to the current date
+		 * @returns {number} timestamp in milliseconds
+		 * @example
+		 * new Date().addMinutes(1)
+		 */
+		addMinutes(minutes: number, seconds?: number, milliseconds?: number): number;
+		/**
+		 * Add a number of seconds to the current date
+		 * @returns {number} timestamp in milliseconds
+		 * @example
+		 * new Date().addSeconds(1)
+		 */
+		addSeconds(seconds: number, milliseconds?: number): number;
+		/**
+		 * Add a number of milliseconds to the current date
+		 * @returns {number} timestamp in milliseconds
+		 * @example
+		 * new Date().addMilliseconds(1)
+		 */
+		addMilliseconds(milliseconds: number): number;
 	}
 }