add findOldest Solutions

findTheOldest/findTheOldest.js

@@ -0,0 +1,16 @@
+const findTheOldest = function(array) {
+  return array.reduce((oldest, currentPerson) => {
+    const oldestAge = getAge(oldest.yearOfBirth, oldest.yearOfDeath)
+    const currentAge = getAge(currentPerson.yearOfBirth, currentPerson.yearOfDeath)
+    return oldestAge < currentAge ? currentPerson : oldest
+  })
+}
+
+const getAge = function(birth, death) {
+  if (!death) {
+    death = new Date().getFullYear();
+  }
+  return death - birth;
+}
+
+module.exports = findTheOldest