added question on Object.keys()

content/questions/object-keys-order/index.md

@@ -0,0 +1,39 @@
+---
+title: Object.keys() output ordering
+tags:
+  - Object
+order: 75
+date: Mon Oct 05 2020 19:48:18 GMT+0530 (India Standard Time)
+answers: 
+  - [name,1,11,age,country,9]
+  - [1,9,11,name,age,country]
+  - [name,age,country,1,11,9]
+  - [1,11,9,name,age,country]
+---
+
+What will be the output of the following code snippet?
+
+```javascript
+
+const json = {
+  "name": "John Doe",
+  "1": "1K",
+  "11": "1M",
+  "age": 27,
+  "country": "India",
+  "9": "9M"
+};
+
+console.log(Object.keys(json));
+
+```
+
+<!-- explanation -->
+
+Answer is B: `[1,9,11,name,age,country]`
+
+Object keys are not randomly ordered, rather it follows the following rule:
+
+First integer keys are picked in sorted order i.e. 1,9,11
+
+Followed by string keys - in order of their occurrence. i.e. name,age,country