Angular2: switchMap not canceling previous http calls

Question

I am trying to use switchMap to cancel any previous http calls in Angular2. The code is basically

var run = ():Observable => {
        var url = \'         


        

Answer 1

You can use Subject but if you do so, you have to manage subscription and publish. If you just want a method returning Observable which cancel requests within a interval, here is how I would do that :

observer: Observer;
debug = 0;

myFunction(someValue) {
    this.observable = new Observable(observer => {
        if (!this.observer) {
            this.observer = observer;
        }

       // we simulate http response time
        setTimeout(() => {
            this.observer.next(someValue);
            this.debug++;
        }, 1000);
    })
    .debounceTime(3000) // We cancel request withing 3s interval and take only the last one
    .switchMap(fn)
    .do(() => {
        console.log("debug", this.debug);
    });
}

Using the same observer all along let us cancel requests according all we want (debounceTime, distinctUntilChanged, ...).