Add solution #2722

Author: JoshCrozier

README.md

@@ -408,6 +408,7 @@
 2695|[Array Wrapper](./2695-array-wrapper.js)|Easy|
 2703|[Return Length of Arguments Passed](./2703-return-length-of-arguments-passed.js)|Easy|
 2721|[Execute Asynchronous Functions in Parallel](./2721-execute-asynchronous-functions-in-parallel.js)|Medium|
+2722|[Join Two Arrays by ID](./2722-join-two-arrays-by-id.js)|Medium|
 2724|[Sort By](./2724-sort-by.js)|Easy|
 3042|[Count Prefix and Suffix Pairs I](./3042-count-prefix-and-suffix-pairs-i.js)|Easy|
 3110|[Score of a String](./3110-score-of-a-string.js)|Easy|

solutions/2722-join-two-arrays-by-id.js

@@ -0,0 +1,32 @@
+/**
+ * 2722. Join Two Arrays by ID
+ * https://leetcode.com/problems/join-two-arrays-by-id/
+ * Difficulty: Medium
+ *
+ * Given two arrays arr1 and arr2, return a new array joinedArray. All the objects in each
+ * of the two inputs arrays will contain an id field that has an integer value.
+ *
+ * joinedArray is an array formed by merging arr1 and arr2 based on their id key. The length
+ * of joinedArray should be the length of unique values of id. The returned array should be
+ * sorted in ascending order based on the id key.
+ *
+ * If a given id exists in one array but not the other, the single object with that id should
+ * be included in the result array without modification.
+ *
+ * If two objects share an id, their properties should be merged into a single object:
+ * - If a key only exists in one object, that single key-value pair should be included in
+ *   the object.
+ * - If a key is included in both objects, the value in the object from arr2 should override
+ *   the value from arr1.
+ */
+
+/**
+ * @param {Array} arr1
+ * @param {Array} arr2
+ * @return {Array}
+ */
+var join = function(arr1, arr2) {
+  const map = new Map();
+  [...arr1, ...arr2].forEach(obj => map.set(obj.id, { ...map.get(obj.id), ...obj }));
+  return Array.from(map.values()).sort((a, b) => a.id - b.id);
+};