Blazor: Component re-renders even when onmousemove is null

[mrpmorris]

Blazor components send a message to the server about mouse-move events even though the @onmousemove event callback has been set to null.

It would be useful if, when building the render tree, Blazor wouldn't include events that are null.

Take this example. Modify the SurveyPrompt in a default template.

<div class="alert alert-secondary mt-4" role="alert" @onmousemove=OnMouseMove>
 ...Omitted for brevity
</div>

@code {
  ..Omitted

  private Action<MouseEventArgs> OnMouseMove { get; set; } = null;

  protected override void OnAfterRender(bool firstRender)
  {
      base.OnAfterRender(firstRender);
      System.Diagnostics.Debug.WriteLine("Rendered SurveyPrompt: " + (OnMouseMove == null));
  }
}

Because OnMouseMove is null the component doesn't need to re-render every time the mouse moves over it.

This would be useful for components that implement events that the consumer can optionally set.

[mkArtakMSFT]

We've moved this issue to the Backlog milestone. This means that it is not going to happen for the coming release. We will reassess the backlog following the current release and consider this item at that time. However, keep in mind that there are many other high priority features with which it will be competing for resources.

[ghost]

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.

[ghost]

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.