Added Converter

src/App.js

 import React, { useEffect, useCallback, useState, useMemo } from "react";
 import logo from "./logo.svg";
 import "./App.css";
+import Converter from './helper/converter';
 
 const Inputs = { toDecimal: "toDecimal", toRoman: "toRoman" };
 
@@ -30,8 +31,8 @@ function App() {
     const romanToBeConverted = toDecimalValue;
     const decimalToBeConverted = toRomanValue;
     return {
-      toDecimal: 499,
-      toRoman: 'CDXCIX'
+      toDecimal: Converter.fromRoman(romanToBeConverted),
+      toRoman: Converter.toRoman(decimalToBeConverted)
     };
   }, [toDecimalValue, toRomanValue]);
 

src/helper/converter.js

+export default class Converter {
+  static Dictionary = {
+    I: 1,
+    V: 5,
+    X: 10,
+    L: 50,
+    C: 100,
+    D: 500,
+    M: 1000
+  };
+  static _dictionaryValues = Object.values(this.Dictionary).reverse();
+  static _dictionaryNames = Object.keys(this.Dictionary).reverse();
+
+  static _maxDecimalGroupSigns = 3;
+
+  static _validateSign(sign) {
+    return sign in this.Dictionary;
+  }
+
+  static _isSignDescribesDecimalGroup(sign) {
+    return String(this.Dictionary[sign]).substring(0, 1) === "5";
+  }
+
+  static _extractRomanSign(sign, value) {
+    if (value / this.Dictionary[sign] >= 1) {
+      return value - this.Dictionary[sign];
+    } else {
+      return false;
+    }
+  }
+
+  static toRoman(decimalValue) {
+    let romanExpression = "";
+    let decimal = decimalValue;
+
+    const calculatedDictionary = this._dictionaryNames.reduce(
+      (dictionary, sign) => {
+        const extractResult = this._extractRomanSign(sign, decimal);
+
+        if (extractResult === 0) {
+          return dictionary;
+        }
+
+        if (typeof extractResult === "number") {
+          decimal = extractResult;
+          dictionary[sign] = dictionary[sign] ? dictionary[sign] + 1 : 1;
+        }
+
+        return dictionary;
+      },
+      {}
+    );
+
+    console.log(calculatedDictionary);
+
+    return romanExpression;
+  }
+
+  static fromRoman(roman) {}
+}