Traveloka Bus Riddle

traveloka-bus.ts

import * as Rx from 'rxjs/Rx';

let currentBus:string = "";

let Bus106Interval = Rx.Observable.interval(3000).map(() => currentBus = ('106'));
let Bus77Interval = Rx.Observable.interval(3000).map(() => currentBus = ('77'));



Bus77Interval.toPromise();


setTimeout(() => {
    Bus106Interval.toPromise();        
}, 1000);


function randomDelay(bottom:number, top:number) {
    return Math.floor( Math.random() * ( 1 + top - bottom ) ) + bottom;
}

Rx.Observable.interval(500)
    .delay(randomDelay(1000, 3000))    
    .map(() => {
        if(currentBus.length > 0){
            console.log(`Taking bus #${currentBus}`);
        }
        
    }).toPromise();