How to change classes of a div element using Blazor

Question

I have a typical div element in a cshtml page in the form:

<div id="loginErrors" class="alert alert-danger hide-errors">@(ErrorMessage)</div> 

pre Blazor, I'd typically use jQuery to add or remove the hide-errors class from the div. However, Blazor is trying to remove the need for JavaScript and I'm trying to use as little JSInterop as possible. Is there a way in Blazor to do this?

so in Blazor I could do:

 @if (!string.IsNullOrEmpty(ErrorMessage))  {      <div id="loginErrors" class="alert alert-danger">@(ErrorMessage)</div>  }  else  {      <div id="loginErrors" class="alert alert-danger hide-errors">@(ErrorMessage)</div>  } 

or using JSinterop :

the Call for removing:

await JSRuntime.Current.InvokeAsync<object>("blazorExtensions.RemoveClass", "loginErrors", "hide-errors"); 

where the function would typically be :

RemoveClass: function (id, classname) {     var tt = '#' + id;     $(tt).removeClass(classname); } 

with similar for adding a class. Both of the above work, but as mentioned. I'm trying to avoid the JSInterop route and I don't like the div element being declared twice even though only one will get into the DOM.

Answer 1

Just like you would in regular Razor:

@if (price>30) {     <p>The price is too high.</p> } 

EDIT For updated question, I guess you want this:

<div class="@((string.IsNullOrEmpty(ErrorMessage)? "hide-errors" : ""))">