Best practice for declaring properties within a class?

In the video, Ashley declares the empty array tokens in the constructor of the Player class.

Testing with the console in the browser, I can see that declaring it in the body of the class is also accepted: it returns a value when an object is instantiated.

I wonder what is considered best practice for declaring properties: declaring in the constructor method like this:

class Player {
  constructor(){
   this.tokens = [];
  }
}

... or in the class body, like this:

class Player {
  constructor(){}
  tokens = [];
}

Obviously we wouldn't be able to pass in a value to the property upon instantiation unless it were declared in the constructor, but if we were planning to use a setter method to provide a value after instantiation instead then is there any benefit to declaring the empty property in the constructor method?