Duplicate code fix.

backend/src/api/common.ts

@@ -0,0 +1,28 @@
+import { TransactionExtended } from '../interfaces';
+
+export class Common {
+  static median(numbers: number[]) {
+    let medianNr = 0;
+    const numsLen = numbers.length;
+    if (numsLen % 2 === 0) {
+        medianNr = (numbers[numsLen / 2 - 1] + numbers[numsLen / 2]) / 2;
+    } else {
+        medianNr = numbers[(numsLen - 1) / 2];
+    }
+    return medianNr;
+  }
+
+  static getFeesInRange(transactions: TransactionExtended[], rangeLength: number) {
+    const arr = [transactions[transactions.length - 1].feePerVsize];
+    const chunk = 1 / (rangeLength - 1);
+    let itemsToAdd = rangeLength - 2;
+
+    while (itemsToAdd > 0) {
+      arr.push(transactions[Math.floor(transactions.length * chunk * itemsToAdd)].feePerVsize);
+      itemsToAdd--;
+    }
+
+    arr.push(transactions[1].feePerVsize);
+    return arr;
+  }
+}