199 words (approximately 1 min)

overview

Some Razor Components modify the HTML <head> element’s content of a page.

HTML <title> Element and PageTitle Component

Set the page’s title with a PageTitle component. This renders the HTML <title> element to a HeadOutlet component:

@page "/set-title"

<h1>Setting title</h1>

<p>Title: @title</p>

<PageTitle>@title</PageTitle>

@code {
    private string title = "Title set by component";
}

HTML <head> Element and HeadContent Component

Set the content of the <head> element with a HeadContent component. This provides content to a HeadOutlet component:

@page "/control-head-content"

<h1>Control <head> content</h1>

<p>Title: @title</p>

<p>Description: @description</p>

<PageTitle>@title</PageTitle>

<HeadContent>
    <meta name="description" content="@description">
</HeadContent>

@code {
    private string description = "Description set by component";
    private string title = "Title set by component";
}

HeadOutlet Component

Renders content provided by HeadContent and PageTitle components.

in blazor wasm

The HeadOutlet component is added to the RootComponents collection in Program.cs:

builder.RootComponents.Add<HeadOutlet>("head::after");

By using the ::after pseudo-selector, contents of the root component appended to existing head contents instead of replacing them.

in blazor server

A component tag helper in Pages/_Host.cshtml renders <head> content for the HeadOutlet component:

<head>
    ...
    <component type="typeof(HeadOutlet)" render-mode="ServerPrerendered" />
</head>

NotFound Component

The NotFound Component in the App Component (App.razor) sets the page title to “Not found”:

<PageTitle>Not found</PageTitle>