Having variables in the constructor vs in the actual class?

Question

The first of the below code examples is what I am doing today, where I initialise the global variables in the constructor.

But would there be any harm in moving the global variables out in the class, as seen in the second example?

class Alert {
  constructor(alert) {
    this.load = JSON.parse('{}');
    this.alert = alert;
    this.#coolDownTime = 0;
  };

  #coolDownTime;
}

vs just doing

class Alert {
  constructor(alert) {
    this.alert = alert;
  };

  #coolDownTime = 0;
  #load = JSON.parse('{}');

}

Answer 1

JavaScript classes are functions, which are objects. (POOP (prototype object-oriented programming)).

Here's an interesting concept, since JavaScript classes are functions, then what do we actually write? JavaScript ES6 classes are just syntactic sugar for prototypes. This means, that both of your ideas are actually the same.
This is exactly how creating a method works.

Here is a good reference: Are ES6 classes just syntactic sugar for the prototypal pattern in Javascript?