Public instance members

• Modifiers: public
• Allowed: camelCase, snake_case
• Leading underscore: allowed

Why This Rule

Public instance members are part of your class's external API. The flexibility here handles several scenarios:

• camelCase: Standard JavaScript/TypeScript convention (userName, orderTotal)
• snake_case: Matching external data structures or database column names (user_id, created_at)
• Leading underscore: Rare, but allowed for "semi-private" public members (discouraged from external use but not forbidden)

Why allow snake_case:

Classes often represent data models mapped from databases or external APIs:

class User {
  public user_id: string; // WHY: snake_case to mirror database/API column naming
  public created_at: Date; // WHY: preserved to avoid mapping layers when receiving external data
  public first_name: string; // WHY: matches external schema
}

Forcing camelCase would require mapping layers everywhere. By allowing both, we let the class naturally mirror its data source while still supporting standard JavaScript conventions.

References:

• TypeScript Handbook - Classes

✅ Good

class Example {
  public userName = 'Alice'; // WHY: camelCase — common and idiomatic
  public user_name = 'Alice'; // WHY: snake_case — acceptable for mapping to external sources or databases
}

// Using a consistent convention per model keeps code readable

❌ Bad

class Example {
  public UserName = 'Alice'; // WHY: PascalCase for instance member is inconsistent with conventions
  public userNameAnd_id = 'x'; // WHY: Mixed naming in a single property is confusing
}