How to load images async with RxJs and perform a method when all loaded

Question

I am trying to convert my promise based code to RxJs but have a hard time to get my head around Rx especially RxJs.

I have a an array with paths.

var         


        

Answer 1

At first you need a function that will create a Observable or Promise for separate image:

function loadImage(imagePath){
   return Rx.Observable.create(function(observer){
     var img = new Image();
     img.src = imagePath;
     img.onload = function(){
       observer.onNext(img);
       observer.onCompleted();
     }
     img.onError = function(err){
       observer.onError(err);
     }
   });
}

Than you can use it to load all images

Rx.Observable
  .fromArray(imagepathes)
  .concatMap(loadImage) // or flatMap to get images in load order
  .toArray()
  .subscribe(function(images){
    // do something with loaded images
  })