how to use switchMap to cancel pending http requests and taking the last subscribe only?

Question

i tried canceling pending http request using subscription.unsubsribe like this:

getAgentList(pageNumber: number, filter: string): any {
   let requestUrl: s         


        

Answer 1

tried and it even did not got out to the server

getAgentList(pageNumber: number, filter: string): any {
    let requestUrl: string = 'api/service/agents_search?ACCT=' 
  +this.accountId;
    if (filter) {
        requestUrl = requestUrl + '&filter=' + filter;
    }
    if (pageNumber) {
        requestUrl = requestUrl + '&pageNumber=' + pageNumber;
    }
    this.$filter.next(requestUrl)

    this.$filter.switchMap(requestUrl => 
    this.backEndCommService.getData(requestUrl))
            .subscribe(
                (res: any) => {
                    let serverResponse: ServerResponse = new 
                    ServerResponse(this.accountId, pageNumber, 
                    res.search_results, 
                    res.resultRows, res.pageSize, res.resultPages)
                    this._agentListData$.next(serverResponse);
                },
               (err: HttpErrorResponse) => {

            console.log('handling error');
      });
}

this line switchMap(requestUrl => this.backEndCommService.getData(requestUrl)) did not made the call and fall silently.....mmmm