const Observable = Rx.Observable;

​

let persons = [

    {

        "firstName":"john",

        "lastName":"public",

        "locationID":"1",

        "departmentID":"100"

    },

    {

        "firstName":"sam",

        "lastName":"smith",

        "locationID":"2",

        "departmentID":"101"

    }

];

​

let departments = [

    { "departmentID": "100", "name": "development" },

    { "departmentID": "101", "name": "sales" }

];

​

let locations = [

    {"locationID": "1", "name": "chicago"},

    {"locationID": "2", "name": "ny"}

];

​

Observable.from(persons)

    .mergeMap(person => {

        let department$ = Observable.from(departments)

            .filter(department => department.departmentID == person.departmentID);

​

        let location$ = Observable.from(locations)

            .filter(location => location.locationID == person.locationID);

​

        return Observable.forkJoin(department$, location$, (department, location) => {

            return {

                'firstName': person.firstName,

                'lastName': person.lastName,

                'location': location.name,

                'department': department.name,

            };

        });

    })

    .toArray()

    .subscribe(result => console.log(result));

​

​

​