any keyword

Rule

NEVER use any keyword, prefer using unknown if you don’t know the type in advance.

• Type safety loss - Using any effectively opts out of TypeScript's type checking for that variable or function, negating the main benefit of using TypeScript in the first place.
• IDE support reduction - You lose intelligent code completion, refactoring tools, and inline documentation that TypeScript-aware IDEs provide.
• Bug introduction risk - any can silently allow type errors that would otherwise be caught during development, leading to runtime errors.
• Code maintenance challenges - Future developers (including yourself) won't understand what data structure is expected, making the code harder to maintain.
• Refactoring difficulties - When refactoring, TypeScript can't help identify where changes are needed for any-typed variables.

Integration

You can add this rule in your tsconfig.json file to ensure there is no any in your code :

tsconfig.json

{
  "compilerOptions": {
    "noImplicitAny": true
  }
}

Examples

🚨 DON’T

const format = (date: Date, displayFormat: any): string => {
  const day = date.getDate();
  const month = date.getMonth() + 1;
  const year = date.getFullYear();

  return `${this.to2digit(day)}/${this.to2digit(month)}/${year}`;
};

type Adapter<T> = {
  adapt(item: any): T;
};

const countryString: any = this.convertSpecificCountryCodes(country);

const warehouseSession: any = {
  warehouseId: warehouse.warehouseId,
  shortWarehouseId: warehouse.shortWarehouseId,
  warehouseName: warehouse.warehouseName,
  address: warehouse.address,
  language: warehouseLanguage,
};

✅ DO

const format = (date: Date, displayFormat: string): string => {
  const day = date.getDate();
  const month = date.getMonth() + 1;
  const year = date.getFullYear();

  return `${this.to2digit(day)}/${this.to2digit(month)}/${year}`;
};

type Adapter<T> = {
  adapt(item: unknown): T;
};

const countryString: string = this.convertSpecificCountryCodes(country);

const warehouseSession: WarehouseSession = {
  warehouseId: warehouse.warehouseId,
  shortWarehouseId: warehouse.shortWarehouseId,
  warehouseName: warehouse.warehouseName,
  address: warehouse.address,
  language: warehouseLanguage,
};