Static & Private Class Fields

What pattern is enhanced by private static fields?

class Config {
  static #instance;
  #settings;
  
  constructor() {
    if (Config.#instance) {
      return Config.#instance;
    }
    this.#loadSettings();
    Config.#instance = this;
  }
  
  #loadSettings() {
    // Load settings
  }
  
  static reset() {
    Config.#instance = null;
  }
}

Factory pattern
Observer pattern
Singleton with reset capability
Private static fields enhance the singleton pattern: 1) Instance storage is truly private, 2) Instance cannot be modified externally, 3) Reset capability is controlled by the class, 4) Loading logic is encapsulated, 5) Prevents multiple instance creation, 6) Enables proper singleton lifecycle management.
Builder pattern

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