How can I get Validators from the formControl directly?

I have an email field, and I added two validators(required, email), I want to check validation status on the input event to call API check dose a member of my system when it's valid, if it's invalid don't to call API and don't show error message on the page.

I will show error message on blur event(focusOut email's input),firstly I used formControl.validator(formControl) to trigger validators and check formControl.valid,I got valid status successful but it will show error message on the page because I subscribed statsuChange to show an error message when status equal to invalid.

currently, I save validators in a variable and pass to initEmailChaingeEvent() to check validation status without statusChange event. It's can work, but I think it's not a good way, here's an example of my implementation:

import { Component, OnInit, ViewChild, ElementRef } from '@angular/core';
import { FormGroup, FormControl, Validators } from '@angular/forms';
import { Observable } from 'rxjs/Observable';
@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent implements OnInit {

  public sampleForm;

  @ViewChild('emailElm')
  emailElm:ElementRef;

  ngOnInit() {
    this.initForm();
  }

  initForm() {
    const emailValidtors = [
      Validators.required,
      Validators.email
    ]
    const emailFC = new FormControl(null, {
      validators :emailValidtors,
      updateOn : 'blur'
    });
    //
    this.sampleForm = new FormGroup({
      'email': emailFC
    });
    //
    this.initEmailChaingeEvent({
      emailFC: emailFC,
      validtors: emailValidtors
    });
  }

  private initEmailChaingeEvent(arg: {
    emailFC: FormControl,
    validtors: any[]
  }) {
    Observable.fromEvent(this.emailElm.nativeElement , 'input')
      .subscribe((event: Event) => {
        const currentEmail = (event.target as HTMLInputElement).value;
        // check is valid
        // **quention** : how can I get validtors from fromcontrol self 
        // if I use  arg.emailFC.validator(arg.emailFC) to ehcek status , it will trigger oberservable in initShowErrorMsgEvent(),
        //  but I just want to know is valid , I don't want to show error msg on UI
        for (const validator of arg.validtors) {         
          const inValid = validator(arg.emailFC);
          if (inValid) {
            return;
          }
        }
        // **do sometheng when all valid**
        // call api ....
      });
  }

  private initShowErrorMsgEvent(arg: {
    fc: FormControl,
  }) {
    arg.fc.statusChanges
      .subscribe((status) => {
        if(status  === 'inValid'){
          // show error msg....
        }
      });
  }


}

<form formGroupName="sampleForm">
  <input formControlName="email" #emailElm />
</form>

from How can I get Validators from the formControl directly?