How do getters and setters work inside a class?

get and set define accessor properties that look like plain fields from the outside but run custom logic on read or write — useful for validation or computed values without changing how consumers interact with the object.

class Temperature {
  #celsius = 0;
  get fahrenheit() { return this.#celsius * 9/5 + 32; }
  set fahrenheit(f) { this.#celsius = (f - 32) * 5/9; }
}
const t = new Temperature();
t.fahrenheit = 98.6;