no-foreach.ts

export class CountriesService implements Mutateble<Country> {
  public mutateSource(
    countries: Country[],
    key: keyof Country,
    value: Country[keyof Country]
  ): Country[] {
    countries.forEach((country) => {
      country[key] = value;
    }); // BAD
 
    for (const country of countries) {
      country[key] = value;
    } // GOOD
 
    for (let i = 0, length = countries.length; i < length; i++) {
      const country = countries[i];
      country[key] = value;
    } // GOOD
 
    return countries;
  }
}