Grouping using maps example (now with es5)

maps-grouping.ts

class Person {
    name!: string;
    age!: number;
    sex!: string;
    public toString = () : string => JSON.stringify(this);
}

const people: Person[] = [
    { age: 25, sex: 'f', name: 'Sue'    },
    { age: 30, sex: 'f', name: 'Angela' },
    { age: 30, sex: 'm', name: 'Joe'    },
    { age: 30, sex: 'm', name: 'Frank'  },
    { age: 35, sex: 'f', name: 'Sarah'  }
];

type AgeGrouping = Map<number, SexGrouping>;
type SexGrouping = Map<string, Array<Person>>;

function getSexGrouping(map: AgeGrouping, age: number): SexGrouping {
    let sexGrouping = map.get(age);
    if (sexGrouping === undefined)
        map.set(age, sexGrouping = new Map<string, Array<Person>>());
    return sexGrouping;
}

function getPeople(map: SexGrouping, sex: string): Array<Person> {
    let people = map.get(sex);
    if (people === undefined)
    map.set(sex, people = new Array<Person>());
    return people;
}

const ageGrouping = new Map<number, SexGrouping>();
for (let person of people) {
    const sexGrouping = getSexGrouping(ageGrouping, person.age);
    const people = getPeople(sexGrouping, person.sex);
    people.push(person);
}

console.log(ageGrouping);