I need to listen if there any changes in the form, make enable/disable SAVE button if there changes or not | Angular

Question

Have issue with listening any changes on a page there is some information, and even if no changes SAVE button active for click

ngOnInit(): void {
        this.createConfigForm()

        this.configFilterForm.valueChanges.pipe(takeUntil(this.unsubscribeAll$)).subscribe(value => {
            value
        })
 }

<!-- ADD BUTTON -->
            <button
                *ngIf="isUpdate()"
                [disabled]="configFilterForm"
                mat-raised-button
                class="add-config-button"
                (click)="onSave()"
                trackClickSnowplow
                id="config-form_save_button"
            >
                <span>SAVE</span>
            </button>

Answer 1

Listen to the form changes like you are doing now, and every time there is a change, enable the button. Disable the button when you click the button, it will stay disabled until change happens. Something like:

configFilterForm: FormGroup;
isDisabled = true;

constructor(private fb: FormBuilder) {
  this.configFilterForm = this.fb.group({
    input1: ['hello']
  });

  this.configFilterForm.valueChanges.pipe(
    takeUntil(this.unsubscribeAll$)
  ).subscribe(value => {
     this.isDisabled = false;
  });
}

And button:

<button [disabled]="isDisabled">Submit</button>

HERE'S A DEMO

BTW, I see you are calling some function *ngIf="isUpdate()" on your button. Please don't do that, they are called on each change detection and can really slow down your application. Use variables instead!