Static Properties and Methods

Static members belong to the class itself, not to individual instances. Use them for behavior or data that is shared across all instances.

What static members are

• Accessed on the class (ClassName.method()), not on instances.
• Useful for utilities, factories, or shared constants.

Static methods

class User {
  constructor(name) {
    this.name = name;
  }
  static fromJSON(json) {
    return new User(json.name);
  }
}

const user = User.fromJSON({ name: "Alice" });

Static properties

class Config {
  static APP_NAME = "MyApp";
  static VERSION = "1.0.0";
}

console.log(Config.APP_NAME);

When to use static members

• Use for:
  • Utility functions that don’t depend on instance state.
  • Factories that create instances (fromJSON, fromId, etc.).
  • Shared constants or configuration.
• Avoid for:
  • Per-instance data (belongs on this).
  • Behavior that depends on instance state.