formatDate function v1.1

src/formatDate.js

@@ -1,14 +1,54 @@
 'use strict';
 
-/**
- * @param {string} date
- * @param {string[]} fromFormat
- * @param {string[]} toFormat
- *
- * @returns {string}
- */
 function formatDate(date, fromFormat, toFormat) {
-  // write code here
+  const prevSplitter = fromFormat[3];
+  const newSplitter = toFormat[3];
+  const rawDate = date.split(prevSplitter);
+  const newRawDate = [];
+
+  function setTheDate(dateType, nextDateType = dateType) {
+    newRawDate[toFormat.indexOf(nextDateType)] =
+      rawDate[fromFormat.indexOf(dateType)];
+  }
+
+  setTheDate('DD');
+  setTheDate('MM');
+
+  if (fromFormat.includes('YYYY') && toFormat.includes('YYYY')) {
+    setTheDate('YYYY');
+  }
+
+  if (fromFormat.includes('YYYY') && toFormat.includes('YY')) {
+    setTheDate('YYYY', 'YY');
+
+    newRawDate[toFormat.indexOf('YY')] = newRawDate[
+      toFormat.indexOf('YY')
+    ].slice(2, 4);
+  }
+
+  if (fromFormat.includes('YY') && toFormat.includes('YYYY')) {
+    if (rawDate[fromFormat.indexOf('YY')] < 30) {
+      newRawDate[toFormat.indexOf('YYYY')] =
+        `20${rawDate[fromFormat.indexOf('YY')]}`;
+    }
+
+    if (rawDate[fromFormat.indexOf('YY')] >= 30) {
+      newRawDate[toFormat.indexOf('YYYY')] =
+        `19${rawDate[fromFormat.indexOf('YY')]}`;
+    }
+  }
+
+  const newDate = newRawDate.join(newSplitter);
+
+  return newDate;
 }
 
+formatDate('2020-02-18', ['YYYY', 'MM', 'DD', '-'], ['YYYY', 'MM', 'DD', '.']);
+
+formatDate('18-02-2020', ['DD', 'MM', 'YYYY', '-'], ['DD', 'MM', 'YY', '/']);
+
+formatDate('20/02/18', ['YY', 'MM', 'DD', '/'], ['YYYY', 'MM', 'DD', '.']);
+
+formatDate('97/02/18', ['YY', 'MM', 'DD', '/'], ['DD', 'MM', 'YYYY', '.']);
+
 module.exports = formatDate;