Classes – Public, Private, Protected

Class Syntax

class Person {
  public name: string;
  private ssn: string; // hidden from outside
  protected birthYear: number; // visible to subclasses

  constructor(name: string, ssn: string, birthYear: number) {
    this.name = name;
    this.ssn = ssn;
    this.birthYear = birthYear;
  }

  public getAge(currentYear: number): number {
    return currentYear - this.birthYear;
  }
}

Private Fields (# syntax – stage 4)

class Secret {
  #token: string;
  constructor(token: string) { this.#token = token; }
  reveal() { return this.#token; }
}

Access Modifiers Summary

Modifier	Visibility
public	Anywhere (default)
protected	Class and subclasses
private	Class only
#private	Class only, enforced at runtime