test getFormattedAmounts

getFormattedAmounts.js

+               let previousTransactions = localStorage.previousTransactions ? JSON.parse(localStorage.previousTransactions) : [],
+                       amountByCount = previousTransactions.reduce(function(memo, transaction) {
+                               var current = memo[transaction.value];
+                               if (!current) {
+                                       current = {
+                                               value: transaction.amount,
+                                               currencyCode: transaction.currencyCode,
+                                               currencySymbol: transaction.currencySymbol,
+                                               count: 0
+                                       };
+                               }
+                               current.count++;
+                               memo[transaction.value] = current;
+                               return memo;
+                       }, {}),
+                       sortedAmounts = Object.keys(amountByCount)
+                               .map((amount) => amountByCount[amount])
+                               .sort((objA, objB) => objB.count > objA.count);