Added solition for #1 in Javascript

leet_1.js

@@ -0,0 +1,17 @@
+// https://leetcode.com/problems/two-sum/submissions/
+// Runtime: 112 ms, faster than 37.73% of JavaScript online submissions for Two Sum.
+
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number[]}
+ */
+var twoSum = function(nums, target) {
+    for(let i = 0; i < nums.length; i++) {
+         for(let y = i + 1; y < nums.length; y++) {
+            if(nums[i] + nums[y] === target) {
+                return [i, y];
+            }
+        }
+    }
+};