Exercise 12: Provide alternative solution (#459)

* feat(12): improve solution by making it more cleaner

* refactor(12): rename `array` to `people`

* feat(12): improve explanation of `??=`

Co-authored-by: MaoShizhong <122839503+MaoShizhong@users.noreply.github.com>

* feat(12): include both solutions

* feat(12): hint to use various array methods

* refactor(12): add semicolon

Co-authored-by: MaoShizhong <122839503+MaoShizhong@users.noreply.github.com>

* feat(12): use block comments instead of line for readability

Co-authored-by: MaoShizhong <122839503+MaoShizhong@users.noreply.github.com>

* refactor(12): remove unnecessary comment

Co-authored-by: MaoShizhong <122839503+MaoShizhong@users.noreply.github.com>

---------

Co-authored-by: MaoShizhong <122839503+MaoShizhong@users.noreply.github.com>

12_findTheOldest/README.md

@@ -6,5 +6,5 @@ Now that you've reached the final exercise, you should be fairly comfortable get
 
 ## Hints
 - You should return the whole person object, but the tests mostly just check to make sure the name is correct.
-- This can be done with a couple of chained array methods, or by using `reduce`.
+- There are many ways of doing this using built-in array methods like `reduce`, or even chaining multiple! 
 - One of the tests checks for people with no death-date.. use JavaScript's Date function to get their age as of today.

12_findTheOldest/solution/findTheOldest-solution.js

@@ -1,5 +1,12 @@
-const findTheOldest = function (array) {
-  return array.reduce((oldest, currentPerson) => {
+const getAge = function (birth, death) {
+  if (!death) {
+    death = new Date().getFullYear();
+  }
+  return death - birth;
+};
+
+const findTheOldest = function (people) {
+  return people.reduce((oldest, currentPerson) => {
     const oldestAge = getAge(oldest.yearOfBirth, oldest.yearOfDeath);
     const currentAge = getAge(
       currentPerson.yearOfBirth,
@@ -9,11 +16,25 @@ const findTheOldest = function (array) {
   });
 };
 
-const getAge = function (birth, death) {
-  if (!death) {
-    death = new Date().getFullYear();
-  }
-  return death - birth;
+/* ALTERNATIVE SOLUTION
+const getAge = function (person) {
+  // The nullish coalescing assignment operator
+  // only does the assignment if the left side is "nullish" (evaluates to undefined or null)
+  // if the left side has any other value, no assignment happens
+  // here, we use ??= to set the current year for our subtraction below only if there is no year of death
+  person.yearOfDeath ??= new Date().getFullYear();
+
+  return person.yearOfDeath - person.yearOfBirth;
 };
 
+const findTheOldest = function (people) {
+  const peopleOldestToYoungest = people.toSorted(
+    (person, nextPerson) => getAge(nextPerson) - getAge(person),
+  );
+
+  const oldestPerson = peopleOldestToYoungest[0];
+  return oldestPerson;
+};
+*/
+
 module.exports = findTheOldest;