add js solution for leetcode 349 and 350

Author: swiftwind0405

README.md

@@ -129,8 +129,8 @@ LeetCode
 |371|[Sum of Two Integers](https://leetcode.com/problems/sum-of-two-integers/description/) | |Easy|
 |367|[Valid Perfect Square](https://leetcode.com/problems/valid-perfect-square/description/) | |Easy|
 |357|[Count Numbers with Unique Digits](https://leetcode.com/problems/count-numbers-with-unique-digits/) | |Medium|
-|350|[Intersection of Two Arrays II](https://leetcode.com/problems/intersection-of-two-arrays-ii/) | |Easy|
-|349|[Intersection of Two Arrays](https://leetcode.com/problems/intersection-of-two-arrays/) | |Easy|
+|350|[Intersection of Two Arrays II](https://leetcode.com/problems/intersection-of-two-arrays-ii/) | [js](./algorithms/intersectionOfTwoArraysII/intersectionOfTwoArraysII.js) |Easy|
+|349|[Intersection of Two Arrays](https://leetcode.com/problems/intersection-of-two-arrays/) | [js](./algorithms/intersectionOfTwoArrays/intersectionOfTwoArrays.js) |Easy|
 |347|[Top K Frequent Elements](https://leetcode.com/problems/top-k-frequent-elements/) | |Medium|
 |345|[Reverse Vowels of a String](https://leetcode.com/problems/reverse-vowels-of-a-string/) | |Easy|
 |344|[Reverse String](https://leetcode.com/problems/reverse-string/) [java](./algorithms/resverseString/Solution.java) | |Easy|

algorithms/intersectionOfTwoArrays/intersectionOfTwoArrays.js

@@ -0,0 +1,13 @@
+var intersection = function(nums1, nums2) {
+    const set = new Set();
+    nums1.forEach(x => set.add(x));
+
+    const res = [];
+    nums2.forEach(y => {
+        if (set.has(y)) {
+            res.push(y);
+            set.delete(y);
+        }
+    })
+    return res;
+};

algorithms/intersectionOfTwoArraysII/intersectionOfTwoArraysII.js

@@ -0,0 +1,21 @@
+var intersect = function(nums1, nums2) {
+    const map = new Map();
+    nums1.forEach(x => {
+        if (map.has(x)) {
+            map.set(x, map.get(x) + 1);
+        } else {
+            map.set(x, 1);
+        }
+    });
+    const res = [];
+    nums2.forEach(y => {
+        if (map.has(y)) {
+            res.push(y);
+            map.set(y, map.get(y) - 1);
+            if(map.get(y) === 0) {
+                map.delete(y);
+            }
+        }
+    });
+    return res;
+};