SwitchMap

switchmap.ts

var source = Observable.create(observer => {

  let valueA = 5; 
  let valueB = 10; 
  

  observer.next(valueA);
  observer.next(valueB);
  
  observer.complete();
 })
    
 source.subscribe((val)=>{
   console.log(val); /// 10 (valueB)
 })