contains duplicate solution

Author: prgmr99

contains-duplicate/prgmr99.js

@@ -0,0 +1,10 @@
+/**
+ * @param {number[]} nums
+ * @return {boolean}
+ */
+var containsDuplicate = function (nums) {
+  const numArrLength = nums.length;
+  const numSetSize = new Set(nums).size;
+
+  return numArrLength !== numSetSize;
+};