Please tell me the behaviour of this in both situations. Why one shows 'window' and the other 'object'. Though they are called in the same manner by callback.

**CASE: 1**

```
let army = {
    minAge: 18,
    maxAge: 27,
    canJoin(user) {
        console.log(this);
    }
  };

function karan(callback){

    callback(); 
}  

karan(army.canJoin);

```

**Result is WINDOW OBJECT**

**CASE: 2**

```
let army = {
    minAge: 18,
    maxAge: 27,
    canJoin(user) {
        console.log(this);
    }
  };

function karan(callback){

    callback(); 
}  

karan( () => army.canJoin());

```

**RESULT: THE OBJECT**