diff --git a/problems/0235.二叉搜索树的最近公共祖先.md b/problems/0235.二叉搜索树的最近公共祖先.md
index a893c191..dffc89e6 100644
--- a/problems/0235.二叉搜索树的最近公共祖先.md
+++ b/problems/0235.二叉搜索树的最近公共祖先.md
@@ -313,63 +313,47 @@ func lowestCommonAncestor(root, p, q *TreeNode) *TreeNode {
 }
 ```
 
-
-JavaScript版本
-> 递归
-
+JavaScript版本：
+1. 使用递归的方法
 ```javascript
-/**
- * Definition for a binary tree node.
- * function TreeNode(val) {
- *     this.val = val;
- *     this.left = this.right = null;
- * }
- */
-
-/**
- * @param {TreeNode} root
- * @param {TreeNode} p
- * @param {TreeNode} q
- * @return {TreeNode}
- */
 var lowestCommonAncestor = function(root, p, q) {
-    if(root.val > p.val && root.val > q.val)
-        return lowestCommonAncestor(root.left, p , q);
-    else if(root.val < p.val && root.val < q.val) 
-        return lowestCommonAncestor(root.right, p , q);
-    return root;
-};
-```
-
-> 迭代
-
-```javascript
-/**
- * Definition for a binary tree node.
- * function TreeNode(val) {
- *     this.val = val;
- *     this.left = this.right = null;
- * }
- */
-
-/**
- * @param {TreeNode} root
- * @param {TreeNode} p
- * @param {TreeNode} q
- * @return {TreeNode}
- */
-var lowestCommonAncestor = function(root, p, q) {
-    while(1) {
-        if(root.val > p.val && root.val > q.val)
-            root = root.left;
-        else if(root.val < p.val && root.val < q.val)
-            root = root.right;
-        else
-            break;
+    // 使用递归的方法
+    // 1. 使用给定的递归函数lowestCommonAncestor
+    // 2. 确定递归终止条件
+    if(root === null) {
+        return root;
+    }
+    if(root.val>p.val&&root.val>q.val) {
+        // 向左子树查询
+        let left = lowestCommonAncestor(root.left,p,q);
+        return left !== null&&left;
+    }
+    if(root.val<p.val&&root.val<q.val) {
+        // 向右子树查询
+        let right = lowestCommonAncestor(root.right,p,q);
+        return right !== null&&right;
     }
     return root;
 };
 ```
+2. 使用迭代的方法
+```javascript
+var lowestCommonAncestor = function(root, p, q) {
+    // 使用迭代的方法
+    while(root) {
+        if(root.val>p.val&&root.val>q.val) {
+            root = root.left;
+        }else if(root.val<p.val&&root.val<q.val) {
+            root = root.right;
+        }else {
+            return root;
+        }
+        
+    }
+    return null;
+};
+```
+
 
 
 -----------------------
diff --git a/problems/0236.二叉树的最近公共祖先.md b/problems/0236.二叉树的最近公共祖先.md
index 2413af1d..7b5deb56 100644
--- a/problems/0236.二叉树的最近公共祖先.md
+++ b/problems/0236.二叉树的最近公共祖先.md
@@ -311,35 +311,34 @@ func lowestCommonAncestor(root, p, q *TreeNode) *TreeNode {
 }
 ```
 
-JavaScript版本
-
+JavaScript版本：
 ```javascript
-/**
- * Definition for a binary tree node.
- * function TreeNode(val) {
- *     this.val = val;
- *     this.left = this.right = null;
- * }
- */
-/**
- * @param {TreeNode} root
- * @param {TreeNode} p
- * @param {TreeNode} q
- * @return {TreeNode}
- */
 var lowestCommonAncestor = function(root, p, q) {
-    if(root === p || root === q || root === null)
-        return root;
-    let left = lowestCommonAncestor(root.left, p , q);
-    let right = lowestCommonAncestor(root.right, p, q);
-    if(left && right)
-        return root;
-    if(!left)
-        return right;
-    return left;
+    // 使用递归的方法
+    // 需要从下到上，所以使用后序遍历
+    // 1. 确定递归的函数
+    const travelTree = function(root,p,q) {
+        // 2. 确定递归终止条件
+        if(root === null || root === p||root === q) {
+            return root;
+        }
+        // 3. 确定递归单层逻辑
+        let left = travelTree(root.left,p,q);
+        let right = travelTree(root.right,p,q);
+        if(left !== null&&right !== null) {
+            return root;
+        }
+        if(left ===null) {
+            return right;
+        }
+        return left;
+    }
+   return  travelTree(root,p,q);
 };
 ```
 
+
+
 -----------------------
 * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)
 * B站视频：[代码随想录](https://space.bilibili.com/525438321)
diff --git a/problems/0501.二叉搜索树中的众数.md b/problems/0501.二叉搜索树中的众数.md
index 1831a7a5..f4b239c3 100644
--- a/problems/0501.二叉搜索树中的众数.md
+++ b/problems/0501.二叉搜索树中的众数.md
@@ -523,52 +523,76 @@ func traversal(root *TreeNode,result *[]int,pre *TreeNode){//遍历统计
 }
 ```
 
-JavaScript版本
-
+JavaScript版本：
+使用额外空间map的方法：
 ```javascript
-/**
- * Definition for a binary tree node.
- * function TreeNode(val, left, right) {
- *     this.val = (val===undefined ? 0 : val)
- *     this.left = (left===undefined ? null : left)
- *     this.right = (right===undefined ? null : right)
- * }
- */
-/**
- * @param {TreeNode} root
- * @return {number[]}
- */
-var findMode = function (root) {
-    let maxCount = 0;
-    let curCount = 0;
-    let pre = null;
-    let res = [];
-    const inOrder = (root) => {
-        if (root === null)
-            return;
-        inOrder(root.left);
-
-        if (pre === null)
-            curCount = 1;
-        else if (pre.val === root.val)
-            curCount++;
-        else
-            curCount = 1;
-        pre = root;
-
-        if (curCount === maxCount)
-            res.push(root.val);
-
-        if (curCount > maxCount) {
-            maxCount = curCount;
-            res.splice(0, res.length);
-            res.push(root.val);
+var findMode = function(root) {
+    // 使用递归中序遍历
+    let map = new Map();
+    // 1. 确定递归函数以及函数参数
+    const traverTree = function(root) {
+        // 2. 确定递归终止条件
+        if(root === null) {
+            return ;
         }
-
-        inOrder(root.right);
-        return;
+        traverTree(root.left);
+         // 3. 单层递归逻辑
+        map.set(root.val,map.has(root.val)?map.get(root.val)+1:1);
+        traverTree(root.right);
     }
-    inOrder(root);
+    traverTree(root);
+    //上面把数据都存储到map
+    //下面开始寻找map里面的
+    // 定义一个最大出现次数的初始值为root.val的出现次数
+    let maxCount = map.get(root.val);
+    // 定义一个存放结果的数组res
+    let res = [];
+    for(let [key,value] of map) {
+        // 如果当前值等于最大出现次数就直接在res增加该值
+        if(value === maxCount) {
+            res.push(key);
+        }
+        // 如果value的值大于原本的maxCount就清空res的所有值，因为找到了更大的
+        if(value>maxCount) {
+            res = [];
+            maxCount = value;
+            res.push(key);
+        }
+    }
+    return res;
+};
+```
+不使用额外空间，利用二叉树性质，中序遍历(有序)：
+```javascript
+var findMode = function(root) {
+    // 不使用额外空间，使用中序遍历,设置出现最大次数初始值为1
+    let count = 0,maxCount = 1;
+    let pre = root,res = [];
+    // 1.确定递归函数及函数参数
+    const travelTree = function(cur) {
+        // 2. 确定递归终止条件
+        if(cur === null) {
+            return ;
+        }
+        travelTree(cur.left);
+        // 3. 单层递归逻辑
+        if(pre.val === cur.val) {
+            count++;
+        }else {
+            count = 1;
+        }
+        pre = cur;
+        if(count === maxCount) {
+            res.push(cur.val);
+        }
+        if(count > maxCount) {
+            res = [];
+            maxCount = count;
+            res.push(cur.val);
+        }
+        travelTree(cur.right);
+    }
+    travelTree(root);
     return res;
 };
 ```