TS Check for JavaScript

Employee.js

// @ts-check
/*jshint esversion: 6 */

const formatter = new Intl.NumberFormat('en-US', {
    style: 'currency',
    currency: 'USD',
});

/**
 * @class {Object} Person
 *
 * @property {string} firstname
 * @property {string} lastname
 * @property {string} age
 */
class Person {
    /**
     * @constructs Person
     * @param {string} firstname - The person's firstname
     * @param {string} lastname - The person's lastname
     * @param {number} age - The person's age
     */
    constructor(firstname, lastname, age) {
        this.firstname = firstname;
        this.lastname = lastname;
        this.age = age;
    }

    /**
     * @method getFullname
     * @memberof Employee
     * @return {string} - The person's fullname
     */
    getFullname() {
        return `${this.firstname} ${this.lastname}`;
    }

    /**
     * @method getAge
     * @memberof Employee
     * @return {number} - The person's age
     */
    getAge() {
        return this.age;
    }

    /**
     * @method toString
     * @memberof Employee
     * @return {string} - 
     */
    toString() {
        return `${this.getFullname()} is ${this.age} years old.`;
    }
}

/**
 * @class {Object} Occupation
 *
 * @property {string} name
 * @property {number} salary
 */
class Occupation {
    /**
     * @constructs Occupation
     * @param {string} name 
     * @param {number} salary 
     */
    constructor(name, salary) {
        this.name = name;
        this.salary = salary;
    }
    /**
     * @method getName
     * @memberof Employee
     * @returns {string}
     */
    getName() {
        return this.name;
    }
    /**
     * @method setName
     * @memberof Employee
     * @param {string} name
     */
    setName(name) {
        this.name = name;
    }

    /**
     * @method getSalary
     * @memberof Employee
     * @returns {number}
     */
    getSalary() {
        return this.salary;
    }
    /**
     * @method setSalary
     * @memberof Employee
     * @param {number} salary
     */
    setSalary(salary) {
        this.salary = salary;
    }
    /**
     * @method toString
     * @memberof Occupation
     * @return {string} - 
     */
    toString() {
        return `Works as a ${this.name}, making ${formatter.format(this.salary)} a year.`;
    }
}

/**
 * @class {Object} Employee
 * @extends Person
 * @property {Occupation} occupation
 */
class Employee extends Person {
    /**
     * @constructs Employee
     * @param {string} firstname - The person's firstname
     * @param {string} lastname - The person's lastname
     * @param {number} age - The person's age
     * @param {Occupation} occupation - The person's occupation
     */
    constructor(firstname, lastname, age, occupation) {
        super(firstname, lastname, age);
        this.occupation = occupation;
    }
    /**
     * @method toString
     * @memberof Employee
     * @return {string} - 
     */
    toString() {
        return `${super.toString()} ${this.occupation.toString()}`;
    }
}

const programmer = new Occupation('Frontend Developer Lead', 150000);
const lalo = new Employee('Eduardo', 'Cancino', 41, programmer);

console.log(
    `${lalo}`
);