solution

src/formatDate.js

@@ -8,7 +8,39 @@
  * @returns {string}
  */
 function formatDate(date, fromFormat, toFormat) {
-  // write code here
+  const dateParts = date.split(fromFormat.at(-1));
+
+  const day = dateParts[fromFormat.indexOf('DD')];
+  const month = dateParts[fromFormat.indexOf('MM')];
+  const year =
+    dateParts[fromFormat.indexOf('YYYY')] ||
+    dateParts[fromFormat.indexOf('YY')];
+
+  return toFormat
+    .map((format) => {
+      switch (format) {
+        case 'DD':
+          return day;
+        case 'MM':
+          return month;
+
+        case 'YYYY':
+          if (year < 100 && year.slice(-2) < 30) {
+            return '20' + year.slice(-2);
+          } else if (year < 100) {
+            return '19' + year.slice(-2);
+          } else {
+            return year;
+          }
+
+        case 'YY':
+          return year.slice(-2);
+        default:
+          return '';
+      }
+    })
+    .slice(0, -1)
+    .join(toFormat.at(-1));
 }
 
 module.exports = formatDate;