MarkupBlockComponent.razor

@using Microsoft.AspNetCore.Components.Rendering
<h1>Markup blocks</h1>

<p>
    This component contains blocks of <em>static</em> HTML markup that will be
    represented in the render instructions as single frames.

    This includes nested elements with <span id="attribute-example">attributes</span>.
</p>

<h2>Dynamic markup</h2>

<p>It's also possible to emit markup blocks from render fragments:</p>

<div id="dynamic-markup-block">
    [@((RenderFragment)EmitMarkupBlock)]
</div>

<button @onclick=@(() => { changeOutput = true; })>Change output</button>

<h2>Markup string</h2>

<p>It's also possible to declare a value of a special type that renders as markup:</p>

@((MarkupString)myMarkup)

@code {
    bool changeOutput;

    string myMarkup = "<p class='markup-string-value'>This is a <em>markup string</em>.</p>";

    void EmitMarkupBlock(RenderTreeBuilder builder)
    {
        // To show we detect and apply changes to markup blocks
        if (!changeOutput)
        {
            builder.AddMarkupContent(0, "Here is <strong id='dynamic-element'>an <em>example</em>.</strong> We support multiple-top-level nodes.");
        }
        else
        {
            builder.AddMarkupContent(0, "<span>The output was <em>changed</em></span> completely.");
        }
    }
}