Need to use another class type in angular model class

Question

I want to use Salary Type for salaries class variable. how can i do it ? please help me

export class Employee {

  id: string = "";
  birth_date: string = "";
  emp_no: string = "";
  first_name: string = "";
  last_name: string = "";
  gender: string = "";
  hire_date: string = "";
  salaries: Salary = "";

  constructor() {
    this.salaries = new Salary;

  }


}

export class Salary {

  id: string = "";
  emp_no: string = "";
  salary: string = "";
  rom_date: string = "";
  to_date: string = "";


}