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HtmlTextWriter.AddAttribute Method (HtmlTextWriterAttribute, String)

Adds the markup attribute and the attribute value to the opening tag of the element that the HtmlTextWriter object creates with a subsequent call to the RenderBeginTag method.

Namespace:  System.Web.UI
Assembly:  System.Web (in System.Web.dll)

public virtual void AddAttribute(
	HtmlTextWriterAttribute key,
	string value


Type: System.Web.UI.HtmlTextWriterAttribute
An HtmlTextWriterAttribute that represents the markup attribute to add to the output stream.
Type: System.String
A string containing the value to assign to the attribute.

Use the AddAttribute overload of the AddAttribute(HtmlTextWriterAttribute, String) method to render a standard markup attribute.

For an instance of any given markup element, the HtmlTextWriter class maintains a list of attributes for that element. When the RenderBeginTag method is called, any attributes that are added by the AddAttribute method are rendered to the opening tag of the element. The list of attributes is then cleared from the HtmlTextWriter.

The coding pattern for rendering markup elements is as follows:

  • Use the AddAttribute method to add any attributes to the element.

  • Use the RenderBeginTag method.

  • Use other methods as needed to render the content found between the element's opening and closing tags.

  • Use the RenderEndTag method.

The following code example shows how to use the AddAttribute overload of the AddAttribute(HtmlTextWriterAttribute, String) method to add an Onclick attribute to a markup element, and then set its value to the following ECMAScript code:


writer.AddAttribute(HtmlTextWriterAttribute.Onclick, "alert('Hello');");

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.