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.
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: