Access Modifiers

Introduction

Access modifiers (also called access specifiers) determine the visibility and accessibility of class members (properties and methods). They are fundamental to encapsulation.

Common Access Modifiers

Modifier	Same Class	Subclass	External
public	✅	✅	✅
protected	✅	✅	❌
private	✅	❌	❌

Code Examples

class BankAccount {
  #balance = 0; // Private field (ES2020+)

  deposit(amount) { this.#balance += amount; }
  getBalance() { return this.#balance; }
}

class Employee {
  public name: string;        // Accessible everywhere
  private salary: number;     // Only within this class
  protected department: string; // Within class and subclasses
  readonly id: number;        // Can only be set in constructor
}

class User:
    def __init__(self, username, email, password):
        self.username = username      # Public
        self._email = email           # Protected (convention)
        self.__password = password    # Private (name mangling)

Best Practices

Default to private — Make fields private; expose only what’s needed
Use public for API — Public members are your contract with consumers
Use protected sparingly — Protected creates coupling to subclasses
Provide getters/setters instead of making fields public

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