feat: add js solution to lc problem: No.0970.Powerful Integers (doocs#397)

Author: zhaocchen

solution/0900-0999/0970.Powerful Integers/README.md

@@ -99,6 +99,30 @@ class Solution {
 }
 ```
 
+### **JavaScript**
+
+```js
+/**
+ * @param {number} x
+ * @param {number} y
+ * @param {number} bound
+ * @return {number[]}
+ */
+var powerfulIntegers = function(x, y, bound) {
+    let res = new Set();
+    for (let i = 1; i < bound; i *= x) {
+        for (let j = 1; j < bound; j *= y) {
+            if ((i + j) <= bound) {
+                res.add(i + j);
+            }
+            if (y == 1) break;
+        }
+        if (x == 1) break;
+    }
+    return [...res];
+};
+```
+
 ### **...**
 
 ```

solution/0900-0999/0970.Powerful Integers/README_EN.md

@@ -91,6 +91,30 @@ class Solution {
 }
 ```
 
+### **JavaScript**
+
+```js
+/**
+ * @param {number} x
+ * @param {number} y
+ * @param {number} bound
+ * @return {number[]}
+ */
+var powerfulIntegers = function(x, y, bound) {
+    let res = new Set();
+    for (let i = 1; i < bound; i *= x) {
+        for (let j = 1; j < bound; j *= y) {
+            if ((i + j) <= bound) {
+                res.add(i + j);
+            }
+            if (y == 1) break;
+        }
+        if (x == 1) break;
+    }
+    return [...res];
+};
+```
+
 ### **...**
 
 ```

solution/0900-0999/0970.Powerful Integers/Solution.js

@@ -0,0 +1,19 @@
+/**
+ * @param {number} x
+ * @param {number} y
+ * @param {number} bound
+ * @return {number[]}
+ */
+ var powerfulIntegers = function(x, y, bound) {
+    let res = new Set();
+    for (let i = 1; i < bound; i *= x) {
+        for (let j = 1; j < bound; j *= y) {
+            if ((i + j) <= bound) {
+                res.add(i + j);
+            }
+            if (y == 1) break;
+        }
+        if (x == 1) break;
+    }
+    return [...res];
+};