[FEATURE]: add TS checklist

typescript/README.md

@@ -1 +1,176 @@
 # TypeScript Best Practices
+
+Think to refer to [JavaScript best practices](../javascript/README.md) before reading this document.
+
+## Consistent Coding Style
+
+**Explanation**: Use the linter to enforce a consistent coding style across the codebase.
+
+- **Installation**:
+
+```bash
+pnpm add --save-dev eslint @eslint/js typescript typescript-eslint
+```
+
+- **Configuration eslint.config.mjs**:
+
+Please refer here for the configuration: https://typescript-eslint.io/getting-started
+
+## Type Annotations
+
+- **Explanation**: Provide type annotations for function arguments and return values to ensure type safety.
+
+```typescript
+function greet(name: string): string {
+  return `Hello, ${name}`;
+}
+```
+
+## Types vs Interfaces
+
+- **Explanation**: Use `type` for simple type definitions and `interface` when you need inheritance/extends functionality.
+
+```typescript
+// Simple types - use Type
+type Point = {
+  x: number;
+  y: number;
+};
+
+type UserRole = "admin" | "user" | "guest";
+
+type ApiResponse<T> = {
+  data: T;
+  status: number;
+  message: string;
+};
+
+// When inheritance is needed - use Interface
+interface BaseEntity {
+  id: string;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+interface User extends BaseEntity {
+  name: string;
+  email: string;
+  role: UserRole;
+}
+
+// When implementing a contract - use Interface
+interface Repository<T> {
+  find(id: string): Promise<T>;
+  save(entity: T): Promise<T>;
+  delete(id: string): Promise<void>;
+}
+```
+
+## Avoid `any` and `unknown`
+
+- **Explanation**: Avoid using `any` and `unknown` types as much as possible to ensure type safety. `any` can be assigned to any type, while `unknown` requires a type assertion to be assigned to another type.
+
+```typescript
+let data: any; // Avoid this
+let dataUser: unknown; // Prefer this over any, but avoid if possible
+let userDataUser: User = dataUser as User; // Necessary type assertion for unknown usage
+
+let userData: User; // Prefer this
+```
+
+## Strict Null Checks
+
+- **Explanation**: Enable strict null checks to prevent null or undefined errors.
+
+```typescript
+let nullableString: string | null = null;
+```
+
+## Use `readonly` for Immutability
+
+- **Explanation**: Use `readonly` for properties that should not be modified after initialization.
+
+```typescript
+interface User {
+  readonly id: number;
+  name: string;
+  age: number;
+}
+```
+
+## Use Utility Types
+
+- **Explanation**: Use TypeScript utility types like `Partial`, `Pick`, `Omit` to manipulate types.
+
+```typescript
+interface User {
+  name: string;
+  age: number;
+  email: string;
+}
+
+type UserWithoutEmail = Omit<User, "email">;
+```
+
+## Use of Enums
+
+- **Explanation**: Use enums to represent a set of named values, improving code readability and maintainability.
+
+  ```typescript
+  enum UserRole {
+    Admin = "Admin",
+    User = "User",
+    Guest = "Guest",
+  }
+
+  function getPermissions(role: UserRole) {
+    switch (role) {
+      case UserRole.Admin:
+        return ["read", "write", "delete"];
+      case UserRole.User:
+        return ["read", "write"];
+      case UserRole.Guest:
+        return ["read"];
+    }
+  }
+  ```
+
+## Use of Literal Types
+
+- **Explanation**: Use literal types for simple sets of values to ensure type safety and flexibility.
+
+  ```typescript
+  type OrderStatus = "Pending" | "Shipped" | "Delivered" | "Cancelled";
+
+  function updateOrderStatus(orderId: number, status: OrderStatus) {
+    // Logic to update order status
+    console.log(`Order ${orderId} is now ${status}`);
+  }
+  ```
+
+## Use of `const` with `as const` for Immutable Objects
+
+- **Explanation**: Use `const` with `as const` to define immutable objects, ensuring that values are not accidentally modified.
+
+  ```typescript
+  const Config = {
+    apiUrl: "https://api.example.com",
+    timeout: 5000,
+    retryAttempts: 3,
+  } as const;
+
+  type ConfigType = typeof Config;
+
+  function initializeApp(config: ConfigType) {
+    console.log(`Initializing app with API URL: ${config.apiUrl}`);
+    // App initialization logic
+  }
+  ```
+
+## Ressources
+
+- [TypeScript GitBook : Un ouvrage open-source sur TypeScript](https://basarat.gitbook.io/typescript/)
+- [Typescriptlang Handbook](https://www.typescriptlang.org/docs/handbook/intro.html)
+- [The Concise TypeScript Book](https://typescript-book.vercel.app/books/the-concise-typescript-book/)
+- [TS Playground](https://www.typescriptlang.org/play)
+- [TS config cheat sheet](https://www.totaltypescript.com/tsconfig-cheat-sheet)