leetcode 225 补充js版解法

animation-simulation/栈和队列/225.用队列实现栈.md

@@ -18,6 +18,7 @@
 
 下面我们来看一下题目代码，也是很容易理解。
 
+Java Code:
 ```java
 class MyStack {
     //初始化队列
@@ -55,3 +56,34 @@ class MyStack {
 
 ```
 
+JS Code:
+```javascript
+var MyStack = function() {
+    this.queue = [];
+};
+
+MyStack.prototype.push = function(x) {
+    this.queue.push(x);
+    if (this.queue.length > 1) {
+        let i = this.queue.length - 1;
+        while (i) {
+            this.queue.push(this.queue.shift());
+            i--;
+        }
+    }
+};
+
+MyStack.prototype.pop = function() {  
+    return this.queue.shift();
+};
+
+MyStack.prototype.top = function() {
+    return this.empty() ? null : this.queue[0];
+
+};
+
+MyStack.prototype.empty = function() {
+    return !this.queue.length;
+};
+```
+