angularangular-reactive-formsvaluechangelistener

ValueChanges on FormGroup is fired onKeyUp and onBlur

My Reactive Angular Form should be submitted on Key Up if the form is valid.

I registerd a subscriber on valueChanges but it is called onKeyUp and onBlur of each input and the form is submitted twice. It seems that this is a known issue (https://github.com/angular/angular/issues/12540) and as a solution distinctUntilChanged is suggested. Unfortunately is seems not to work in my case. The submit is fired immediately no matter what time I set and still fired twice.

this.myFormGroup.valueChanges
  .pipe(debounceTime(2000), distinctUntilChanged())
  .subscribe(() => {
    if (this.myFormGroup.valid) {
      this.submitForm();
    }
  });

Does someone have an idea what could be my mistake with distinctUntilChanged? Or is there another method to prevent valueChanges to be fired onKeyUp and onBlur?

Solution

  • distinctUntilChanged uses === comparison by default, object references must match , myFormGroup will emit an object in every change and these objects are not the same reference

    try to add custom method to handle changes

    distinctUntilChanged((p: any, n: any) => JSON.stringify(p) === JSON.stringify(n))

    stackblitz demo

    distinctUntilChanged