Question: I was playing with below javascript code. Understanding of `Object.defineProperty()` and I am facing a strange issue with it. When I try to execute below code in the browser or in the VS code the output is not as expected whereas if I try to debug the code the output is correct

When I debug the code and evaluate the profile I can see the `name & age` property in the object
But at the time of output, it only shows the `name` property

```js
//Code Snippet 
let profile = {
  name: 'Barry Allen',
}

// I added a new property in the profile object.
Object.defineProperty(profile, 'age', {
  value: 23,
  writable: true
})

console.log(profile)
console.log(profile.age)
```

Now expected output here should be 

```
{name: "Barry Allen", age: 23}
23

```

but I get the output as.
Note that I am able to access the `age` property defined afterwards. 
I am not sure why the `console.log()` is behaving this way.

```
{name: "Barry Allen"}
23 

```

Answer: 
You should set `enumerable` to `true`. In `Object.defineProperty` its `false` by default. According to [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/defineProperty#Description).

> 
> **enumerable**  
>   
> 
> `true` if and only if this property shows up during enumeration of the properties on the corresponding object.  
>   
> 
> **Defaults to false.**
> 
> 
> 

Non-enumerable means that property will not be shown in `Object.keys()` or `for..in` loop neither in console

```js
let profile = {
    name: 'Barry Allen',
}

// I added a new property in the profile object.

Object.defineProperty(profile , 'age', {
    value: 23,
    writable: true,
    enumerable: true
})
console.log(profile)
console.log(profile.age)
```

All the properties and methods on `prototype` object of built-in classes are non-enumerable. Thats is the reason you can call them from instance but they don't appear while iterating.

To get all properties(including non-enumerable)[`Object​.get​OwnProperty​Names()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/getOwnPropertyNames).

```js
let profile = {
    name: 'Barry Allen',
}

// I added a new property in the profile object.

Object.defineProperty(profile , 'age', {
    value: 23,
    writable: true,
    enumerable: false
})
for(let key in profile) console.log(key) //only name will be displayed.

console.log(Object.getOwnPropertyNames(profile)) //You will se age too
```
Whenever you use".defineProperty" method of object. You should better define all the properties of the descriptor. Because if you don't define other property descriptor then it assumes default values for all of them which is false. So your console.log checks for all the enumerable : true properties and logs them.

```
//Code Snippet 
let profile = {
  name: 'Barry Allen',
}

// I added a new property in the profile object.
Object.defineProperty(profile, 'age', {
  value: 23,
  writable: true,
  enumerable : true,
  configurable : true
})

console.log(profile)
console.log(profile.age)

```