Microsoft.AspNetCore.Razor by Microsoft

<PackageReference Include="Microsoft.AspNetCore.Razor" Version="2.1.0" />

 TagHelper

public abstract class TagHelper : ITagHelper, ITagHelperComponent
An abstract base class for ITagHelper.
public virtual int Order { get; }

When a set of ITagHelpers are executed, their Init's are first invoked in the specified Order; then their ProcessAsync's are invoked in the specified Order. Lower values are executed first.

protected TagHelper()

public virtual void Init(TagHelperContext context)

Initializes the ITagHelper with the given context. Additions to Items should be done within this method to ensure they're added prior to executing the children.

public virtual void Process(TagHelperContext context, TagHelperOutput output)

Synchronously executes the TagHelper with the given context and output.

public virtual Task ProcessAsync(TagHelperContext context, TagHelperOutput output)

Asynchronously executes the TagHelper with the given context and output.