[Fix] correct Guide article example for Iterate Through the Keys of an Object with a for...in Statement (#35197)

* fix: added dot btwn [user] and online

* fix: corrected example for other languages

guide/chinese/certifications/javascript-algorithms-and-data-structures/basic-data-structures/-iterate-through-the-keys-of-an-object-with-a-for...in-statement/index.md

@@ -13,11 +13,11 @@ localeTitle:  使用for ... in Statement中的对象键迭代
 ### 例1：
 
 ```javascript
-for (let user in obj) { 
-    if(obj.user.online === true) { 
-      //code 
-    } 
-  } 
+for (let user in obj) {
+  if(obj.user.online === true) {
+    //code
+  }
+}
 ```
 
 *   示例2演示了如何使用`[square-bracket]`表示法执行代码。
@@ -25,11 +25,11 @@ for (let user in obj) {
 ### 例2：
 
 ```javascript
-for (let user in obj) { 
-    if(obj[user]online === true) { 
-      //code 
-    } 
-  } 
+for (let user in obj) {
+  if(obj[user].online === true) {
+    //code
+  }
+}
 ```
 
 ### 解：