How to detect changes in Angular2 forms

Question

How to detect changes in Angular2 forms

Exploring Angular2 4.0, I've created a FormGroup structured as follows:

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

Wondering if it's feasible to subscribe to valueChanged individually for specific fields?

I'm trying to avoid monitoring changes on input c, hence the conventional method below doesn't seem effective:

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

angular typescript angular2-forms

Answer 1

Answer №1

Separate subscriptions can be added for FormControl a and b.

this.heroForm.controls["a"].valueChanges.subscribe(data => {
 // Perform an action
});

this.heroForm.controls["b"].valueChanges.subscribe(data => {
 // Perform an action
});

Answer 2

Separate subscriptions can be added for FormControl a and b.

this.heroForm.controls["a"].valueChanges.subscribe(data => {
 // Perform an action
});

this.heroForm.controls["b"].valueChanges.subscribe(data => {
 // Perform an action
});

Answer 3

Answer №2

  
//access form reference
@ViewChild('myForm') myForm;

//add ngAfterViewInit method to your component and include the following code
//alternatively, you can also use the same code with ngOnInit

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

This snippet will provide you with updated field data.

Answer 4

  
//access form reference
@ViewChild('myForm') myForm;

//add ngAfterViewInit method to your component and include the following code
//alternatively, you can also use the same code with ngOnInit

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

This snippet will provide you with updated field data.

Answer 5

Answer №3

          Monitoring changes in the form values
            .pipe(
              waiting for half a second before reacting, 
              only triggering if new value is different from previous
            )
            .subscribe((updatedForm) => {
              Outputting updated form values to console
            });

Answer 6

          Monitoring changes in the form values
            .pipe(
              waiting for half a second before reacting, 
              only triggering if new value is different from previous
            )
            .subscribe((updatedForm) => {
              Outputting updated form values to console
            });

How to detect changes in Angular2 forms

Answer №1

Answer №2

Answer №3

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