var people = Rx.Observable.of('Jerry', 'Anna');

​

function map(source, callback) {

    return Rx.Observable.create((observer) => {

        source.subscribe(

            (value) => { 

                try{

                    observer.next(callback(value));

                } catch(e) {

                    observer.error(e);

                }

            },

            (err) => { observer.error(err); },

            () => { observer.complete() }

        )

    })

}

​

var helloPeople = map(people, (item) => item + ' Hello~');

​

helloPeople.subscribe(console.log);