Angular reactive forms key changes detection

Question

Given valueChanges listener with Angular Reactive Forms

this.companyForm.valueChanges.subscribe((value) => {
  console.log('setChangesListener value', value);
});

How do I find which field was changed exactly?

Answer 1

There's no way to see which field changed from the top level form subscription.

---

However, you can individually subscribe to form controls and that way you know exactly which field changed:

Object.entries(this.formGroup.controls).forEach(value => {
  const [key, control] = value;
  control.valueChanges.subscribe(
    (val) => {
      console.log(key, val);
    },
  );
});