Mayrlabs Language Typescript

TypeScript Code Doctrine

TypeScript is NOT optional. We use it to structurally guarantee application integrity at build time, not merely for editor autocompletion.

The Iron Law

Never use any unless absolutely necessary and heavily justified with a comment.

Core Principles

1. Strict Everything: Ensure strict: true is in tsconfig.json. This implies no implicit anys and strict null checks.
2. Layered Architecture: Use strict DTOs (Data Transfer Objects) and clear interfaces for communication between your Controllers, Services, and Repositories.
3. Interfaces vs Types: Use interface for structural definitions (objects, classes) and extendibility. Use type for unions, intersections, and primitives. Be consistent.
4. Enums are Banned: Avoid TS enum. They transpile to bloated reverse-mapped objects and cause runtime vs build-time confusion. Use const objects or union types (type Status = 'active' | 'inactive').

Best Practices

• Explicit Return Types: Always define exact return types for exported functions and API boundaries.
• Type Narrowing: Use Type Guards (isUser(obj)) instead of dangerous type assertions (obj as User) whenever the source of data is external.
• Utility Types: Master and utilize Omit, Pick, Partial, and Readonly instead of manually duplicating type structures.

Error Handling

Never throw plain strings. Always throw custom Error classes that extend native Error so that instanceof narrowing can be used in your catch blocks.

export class ResourceNotFoundError extends Error {
  constructor(message: string) {
    super(message);
    this.name = 'ResourceNotFoundError';
  }
}

Source: MayR-Labs/skills — distributed by TomeVault.