Angular2: Detect form changes

Question

In Angular2 4.0 I have a FormGroup looking like this:

this.form = this._fb.group({
      a: ['', [Validators.required]],
      b: ['', [Validators.required]],
      c: ['', [Validators.required]],
    });

Is it possible to subscribe valueChanged on individual fields?

I dont want to detect changes on input c, so the below approach does not work:

this.form.valueChanges.debounceTime(400).subscribe(data => {
     // Do something
    });

Answer 1

You can add separate subscriptions for FormControl a and b.

this.heroForm.controls["a"].valueChanges.subscribe(data => {
 // Do something
});

this.heroForm.controls["b"].valueChanges.subscribe(data => {
 // Do something
});

Answer 2

  
//get form ref  
@ViewChild('myForm') myForm;

//implement afterview init to your class and use
// or you can use same code with ngOnInit

ngAfterViewInit(){
  this.myForm.valueChanges.debounceTime(500).subscribe(data =>            console.log('Form changes', data));
}

You can use this code, it will give you changed field data also.