Access Modifiers: public, private, protected — TypeScript Reference, Syntax & Examples

Syntax

public prop: type;
private prop: type;
protected prop: type;

Examples

The Three Modifiers

Controlling exactly where each property/method can be accessed from.

class BankAccount {
  public accountHolder: string;
  private balance: number;
  protected accountNumber: string;

  constructor(holder: string, initialBalance: number, accountNumber: string) {
    this.accountHolder = holder;
    this.balance = initialBalance;
    this.accountNumber = accountNumber;
  }

  public getBalance(): number {
    return this.balance; // accessing private balance is fine from WITHIN the class
  }
}

const account = new BankAccount("Alice", 1000, "ACC-001");
console.log(account.accountHolder); // OK - public
// console.log(account.balance);      // Error - private

protected in Subclasses

protected members remain accessible to subclasses, unlike private ones.

class SavingsAccount extends BankAccount {
  showAccountNumber(): string {
    return this.accountNumber; // OK - protected is accessible in subclasses
    // return this.balance;    // Error - private is NOT accessible, even in a subclass
  }
}

Best practices

Default to private for internal implementation details, exposing only what genuinely needs to be part of the class's public API
Use protected specifically when subclasses legitimately need access to a member that outside code should not have
Remember these modifiers are compile-time only - they are erased when compiled to JavaScript and offer no runtime protection, unlike the # private field syntax
Use JavaScript's native #privateField syntax instead of the private keyword when you need genuine runtime privacy, not just compile-time checking

Runtime & versions

Compiled to JavaScript. Feature availability depends on the language and runtime version used by your project; consult the official reference below.

TypeScript Handbook

Specifications & further reading

TypeScript Handbook