feat: nextRoman, previousRoman && map

README.md

@@ -302,6 +302,67 @@ console.log(roman.range(7));
 // Returns [ 'I', 'II', 'III', 'IV', 'V', 'VI', 'VII' ]
 ```
 
+### ⏭️ Get the next Roman numeral: `nextRoman`
+
+```ts
+/**
+ * Get the next Roman numeral
+ * @param value Current Roman numeral
+ * @returns { string } Next Roman numeral
+ * @throws { Error } When the input is invalid or out of range
+ */
+export function nextRoman(value: string): string {}
+```
+
+🔵 <b>Example</b>
+
+```js
+console.log(roman.nextRoman("XIV"));
+
+// Returns XV
+```
+
+### ⏮️ Get the previous Roman numeral: `prevRoman`
+
+```ts
+/**
+ * Get the previous Roman numeral
+ * @param value Current Roman numeral
+ * @returns { string } Previous Roman numeral
+ * @throws { Error } When the input is invalid or out of range
+ */
+export function previousRoman(value: string): string {}
+```
+
+🔵 <b>Example</b>
+
+```js
+console.log(roman.previousRoman("XIV"));
+
+// Returns XIII
+```
+
+### 🔀 Map an array of general inputs to either numbers or Roman numerals: `map`
+
+```ts
+/**
+ * Map an array of general inputs to either numbers or Roman numerals
+ * @param expected { string } Expected response type
+ * @param args { general[] } Array of general inputs
+ * @returns { general[] } Mapped array of numbers or Roman numerals
+ * @throws { Error } When any of the inputs are invalid or out of range
+ */
+export function map(expected: "number" | "roman", args: general[]): general[] {}
+```
+
+🔵 <b>Example</b>
+
+```js
+console.log(roman.map("roman", [1, 2, 3, 4, 5]));
+
+// Returns [ 'I', 'II', 'III', 'IV', 'V' ]
+```
+
 ## ✨ Found this project useful?
 
 If you found this project useful, or you like what you see, then please consider giving it a ⭐️ on GitHub and sharing it with your social media folks 🙂.

index.js

@@ -1,6 +1,9 @@
 "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });
-exports.table =
+exports.map =
+  exports.previousRoman =
+  exports.nextRoman =
+  exports.table =
   exports.random =
   exports.min =
   exports.max =
@@ -431,3 +434,39 @@ function table(start, end) {
   return result;
 }
 exports.table = table;
+/**
+ * Get the next Roman numeral
+ * @param value Current Roman numeral
+ * @returns { string } Next Roman numeral
+ * @throws { Error } When the input is invalid or out of range
+ */
+function nextRoman(value) {
+  return toRoman(fromRoman(value) + 1);
+}
+exports.nextRoman = nextRoman;
+/**
+ * Get the previous Roman numeral
+ * @param value Current Roman numeral
+ * @returns { string } Previous Roman numeral
+ * @throws { Error } When the input is invalid or out of range
+ */
+function previousRoman(value) {
+  return toRoman(fromRoman(value) - 1);
+}
+exports.previousRoman = previousRoman;
+/**
+ * Map an array of general inputs to either numbers or Roman numerals
+ * @param expected { string } Expected response type
+ * @param args { general[] } Array of general inputs
+ * @returns { general[] } Mapped array of numbers or Roman numerals
+ * @throws { Error } When any of the inputs are invalid or out of range
+ */
+function map(expected, args) {
+  if (expected === "number") {
+    return args.map((item) => validateGeneral(item));
+  } else if (expected === "roman") {
+    return args.map((item) => toRoman(validateGeneral(item)));
+  }
+  return [];
+}
+exports.map = map;

package.json

@@ -1,6 +1,6 @@
 {
   "name": "toroman",
-  "version": "1.2.0",
+  "version": "2.0.1",
   "description": "Convert any number less than 4000 to roman numerals and back to integer",
   "main": "index.js",
   "scripts": {

src/index.ts

@@ -507,3 +507,43 @@ export function table(
 
     return result;
 }
+
+/**
+ * Get the next Roman numeral
+ * @param value Current Roman numeral
+ * @returns { string } Next Roman numeral
+ * @throws { Error } When the input is invalid or out of range
+ */
+export function nextRoman(value: string): string {
+    return toRoman(fromRoman(value) as number + 1);
+}
+
+/**
+ * Get the previous Roman numeral
+ * @param value Current Roman numeral
+ * @returns { string } Previous Roman numeral
+ * @throws { Error } When the input is invalid or out of range
+ */
+export function previousRoman(value: string): string {
+    return toRoman(fromRoman(value) as number - 1);
+}
+
+/**
+ * Map an array of general inputs to either numbers or Roman numerals
+ * @param expected { string } Expected response type
+ * @param args { general[] } Array of general inputs
+ * @returns { general[] } Mapped array of numbers or Roman numerals
+ * @throws { Error } When any of the inputs are invalid or out of range
+ */
+export function map(
+    expected: "number" | "roman",
+    args: general[]
+): general[] {
+    if (expected === "number") {
+        return args.map((item) => validateGeneral(item));
+    } else if (expected === "roman") {
+        return args.map((item) => toRoman(validateGeneral(item)) as string);
+    }
+
+    return [];
+}

src/tests/index.test.ts

@@ -9,7 +9,7 @@ import {
     sum,
     toRoman,
     max,
-    min, random, table, validateGeneral
+    min, random, table, validateGeneral, nextRoman, map, previousRoman
 } from "../index";
 
 describe("getCount", () => {
@@ -693,3 +693,24 @@ describe("validateGeneral", () => {
         }
     });
 });
+
+describe("nextRoman", () => {
+    test("should return II when I is given", () => {
+        expect(nextRoman("I")).toBe("II");
+    });
+});
+
+describe("previousRoman", () => {
+    test("should return I when II is given", () => {
+        expect(previousRoman("II")).toBe("I");
+    });
+});
+
+describe("map", () => {
+    test("should map an array of numbers to roman numerals", () => {
+        const input = [1, 2, 3, 4, 5];
+        const expected = ["I", "II", "III", "IV", "V"];
+        const result = map("roman", input);
+        expect(result).toEqual(expected);
+    });
+});

tests/index.test.js

@@ -610,3 +610,21 @@ describe("validateGeneral", () => {
     }
   });
 });
+describe("nextRoman", () => {
+  test("should return II when I is given", () => {
+    expect((0, index_1.nextRoman)("I")).toBe("II");
+  });
+});
+describe("previousRoman", () => {
+  test("should return I when II is given", () => {
+    expect((0, index_1.previousRoman)("II")).toBe("I");
+  });
+});
+describe("map", () => {
+  test("should map an array of numbers to roman numerals", () => {
+    const input = [1, 2, 3, 4, 5];
+    const expected = ["I", "II", "III", "IV", "V"];
+    const result = (0, index_1.map)("roman", input);
+    expect(result).toEqual(expected);
+  });
+});