done

src/formatDate.js

@@ -8,7 +8,56 @@
  * @returns {string}
  */
 function formatDate(date, fromFormat, toFormat) {
-  // write code here
+  const separator = fromFormat[fromFormat.length - 1];
+  const splittedDate = date.split(separator);
+
+  const result = [];
+
+  for (let i = 0; i < toFormat.length - 1; i++) {
+    const firstLetter = toFormat[i][0];
+
+    for (const el of fromFormat) {
+      if (el.includes(firstLetter)) {
+        const index = fromFormat.indexOf(el);
+
+        result[i] = splittedDate[index];
+      }
+    }
+  }
+
+  for (const el of toFormat) {
+    if (el.includes('Y') && el.length === 2) {
+      const index = toFormat.indexOf(el);
+
+      if (result[index].length === 2) {
+        return result.join(toFormat[toFormat.length - 1]);
+      }
+
+      if (result[index].length === 4) {
+        result[index] = result[index].slice(-2);
+
+        return result.join(toFormat[toFormat.length - 1]);
+      }
+    }
+
+    if (el.includes('Y') && el.length === 4) {
+      const index = toFormat.indexOf(el);
+
+      if (result[index].length === 2) {
+        if (+result[index] < 30) {
+          result[index] = 20 + result[index];
+
+          return result.join(toFormat[toFormat.length - 1]);
+        } else {
+          result[index] = 19 + result[index];
+
+          return result.join(toFormat[toFormat.length - 1]);
+        }
+      }
+    }
+  }
+
+  return result.join(toFormat[toFormat.length - 1]);
 }
 
 module.exports = formatDate;