Private static members

• Modifiers: private, static
• Allowed: camelCase, PascalCase, UPPER_CASE
• Leading underscore: forbidden
• Debatable: yes, we don't have docs online for this one yet. So we allow multiple formats for different use cases, including public static members, but forbid underscore to avoid redundancy.

Why This Rule

Private static members are class-level internals - shared across all instances but not exposed externally.

Allowed formats:

• camelCase: For internal helpers and caches that follow native-like JS naming
• PascalCase: For singleton instances, caches, or shared resources
• UPPER_CASE: For internal constants

No underscore: The private keyword is explicit enough - adding an underscore is redundant.

Common use cases:

class DatabaseService {
  // Singleton instance (private static)
  private static Instance: DatabaseService; // WHY: PascalCase used for private static instance object

  // Shared cache (private static)
  private static QueryCache = new Map(); // WHY: PascalCase acceptable for caches or shared resources

  // Internal helper (private static)
  private static computeKey(value: string) {
    return value.trim();
  } // WHY: camelCase for helper method

  // Internal constant (private static)
  private static readonly MAX_POOL_SIZE = 10; // WHY: UPPER_CASE for internal constant
}

Private statics often manage class-level state or configuration. camelCase works well for internal helper methods and caches, PascalCase for object instances, while UPPER_CASE works for true constants.

References:

• TypeScript Handbook - Static Members

✅ Good

class Example {
  private static fooBar = 1; // WHY: camelCase allowed for internal helpers/caches
  private static FooBar = 2; // WHY: PascalCase allowed for instances
  private static FOO_BAR = 3; // WHY: UPPER_CASE for constants
}

❌ Bad

class Example {
  private static _FooBar = 1; // WHY: leading underscore forbidden — redundant with `private`
}