feat: add js solution to lc problem: No.1518

Author: Qiu-IT

solution/1500-1599/1518.Water Bottles/README.md

@@ -145,6 +145,24 @@ class Solution {
 }
 ```
 
+### **JavaScript**
+
+```js
+/**
+ * @param {number} numBottles
+ * @param {number} numExchange
+ * @return {number}
+ */
+var numWaterBottles = function (numBottles, numExchange) {
+    let sum = numBottles;
+    while (numBottles >= numExchange) {
+        numBottles = numBottles - numExchange + 1;
+        sum++;
+    }
+    return sum;
+};
+```
+
 ### **...**
 
 ```

solution/1500-1599/1518.Water Bottles/README_EN.md

@@ -117,6 +117,24 @@ class Solution {
 }
 ```
 
+### **JavaScript**
+
+```js
+/**
+ * @param {number} numBottles
+ * @param {number} numExchange
+ * @return {number}
+ */
+var numWaterBottles = function (numBottles, numExchange) {
+    let sum = numBottles;
+    while (numBottles >= numExchange) {
+        numBottles = numBottles - numExchange + 1;
+        sum++;
+    }
+    return sum;
+};
+```
+
 ### **...**
 
 ```

solution/1500-1599/1518.Water Bottles/Solution.js

@@ -0,0 +1,13 @@
+/**
+ * @param {number} numBottles
+ * @param {number} numExchange
+ * @return {number}
+ */
+var numWaterBottles = function (numBottles, numExchange) {
+    let sum = numBottles;
+    while (numBottles >= numExchange) {
+        numBottles = numBottles - numExchange + 1;
+        sum++;
+    }
+    return sum;
+};