feat: add js solution to lc problem: No.0476

Author: rain84

solution/0400-0499/0476.Number Complement/README.md

@@ -122,6 +122,18 @@ function findComplement(num: number): number {
 }
 ```
 
+#### JavaScript
+
+```js
+/**
+ * @param {number} num
+ * @return {number}
+ */
+var findComplement = function(num) {
+    return num ^ (2 ** num.toString(2).length - 1);
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

solution/0400-0499/0476.Number Complement/README_EN.md

@@ -116,6 +116,18 @@ function findComplement(num: number): number {
 }
 ```
 
+#### JavaScript
+
+```js
+/**
+ * @param {number} num
+ * @return {number}
+ */
+var findComplement = function(num) {
+    return num ^ (2 ** num.toString(2).length - 1);
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

solution/0400-0499/0476.Number Complement/Solution.js

@@ -0,0 +1,7 @@
+/**
+ * @param {number} num
+ * @return {number}
+ */
+var findComplement = function (num) {
+    return num ^ (2 ** num.toString(2).length - 1);
+};