types, maps, iterators

GradeShool.ts

// https://www.typescriptlang.org/docs/handbook/release-notes/typescript-1-4.html
// https://exercism.io/tracks/typescript/exercises/grade-school/solutions/0798baf5852e4b6e95220a1cbf894eb0
// https://www.digitalocean.com/community/tutorials/typescript-type-alias
type RosterType<T> = Map<T, string[]>;

class GradeSchool{
    private roster: RosterType<number> = new Map();

    public studentRoster(): RosterType<string> {
        const strRoster: RosterType<string> = new Map();
        for(const key of this.roster.keys()){
            strRoster.set(key.toString(), this.studentsInGrade(key));
        }
        return strRoster;
    }

    public addStudent(name: string, grade: number){
        let existingStudents = (this.roster.get(grade) || []).concat(name);
        this.roster.set(grade, existingStudents);
    }

    public studentsInGrade(grade: number): any{
        return (this.roster.get(grade) || []).sort().slice();
    }
}


export default GradeSchool;