When does the StateHasChanged method call automatically?

The StateHasChanged method is called whenever a bound property is changed or a UI event triggered for an instance. This notifies the Blazor that the component should rerender it.

For example, when a button is clicked in the index page, the index component rerenders (no need to call StateHasChanged) because the button’s parent is an index; but when it has a child component it has be notified to render as the parent has changed.