How to watch all FormControls ValueChanges except specific control?

Question

I have a form that do a computation whenever a control input value changes.

Here is my form_group looks like:

form_group = this.fb.group         


        

Answer 1

You can merge individual valueChanges Observables into one like so :

Observable.merge(
    [ control1.valueChanges,
      control2.valueChanges ]
  ).subscribe(() => {
    // do your computation
  });