Add Task Solution

src/formatDate.js

@@ -7,8 +7,51 @@
  *
  * @returns {string}
  */
+function convertYear(year, fromFormat, toFormat) {
+  if (
+    (fromFormat.length === 2 && toFormat.length === 2) ||
+    (fromFormat.length === 4 && toFormat.length === 4)
+  ) {
+    return year;
+  }
+
+  if (fromFormat.length === 4 && toFormat.length === 2) {
+    return year.slice(year.length - 2);
+  }
+
+  return year < 30 ? '20'.concat(year) : '19'.concat(year);
+}
+
 function formatDate(date, fromFormat, toFormat) {
   // write code here
+  const fromSeparator = fromFormat[fromFormat.length - 1];
+  const dateParts = date.split(fromSeparator);
+  const fromFormatParts = fromFormat.slice(0, fromFormat.length - 1);
+  const fromFormatObj = fromFormatParts.reduce((previous, current, index) => {
+    return {
+      ...previous,
+      [current]: dateParts[index],
+    };
+  }, {});
+
+  const yearFromFormat = fromFormatParts.find((format) => format.includes('Y'));
+
+  const toSeparator = toFormat[toFormat.length - 1];
+  const toFormatParts = toFormat.slice(0, toFormat.length - 1);
+
+  return toFormatParts
+    .reduce((prevDateParts, currentPartFormat) => {
+      const isYear = currentPartFormat.includes('Y');
+      const year = convertYear(
+        fromFormatObj[yearFromFormat],
+        yearFromFormat,
+        currentPartFormat,
+      );
+      const datePart = isYear ? year : fromFormatObj[currentPartFormat];
+
+      return [...prevDateParts, datePart];
+    }, [])
+    .join(toSeparator);
 }
 
 module.exports = formatDate;