Angular2：检测表单变化

Question

在 Angular2 4.0 中，我有一个 FormGroup 看起来像这样：

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

是否可以在个别领域订阅 valueChanged？

我不想检测输入的变化 c，所以下面的方法不起作用：

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

Answer 1

您可以为 FormControl a 和 b 添加单独的订阅。

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.

Answer 3

          this.form.valueChanges
            .pipe(
              debounceTime(500), // Wait for 0.5
              distinctUntilChanged() //  execute only if a different value is emitted
            )
            .subscribe((newForm) => {
              console.log(newForm);
            });

Angular2：检测表单变化

Angular2: Detect form changes

typescript

angular2-forms

angular