5.5 HyperLink Control

A HyperLink control looks similar to a LinkButton control. However, there is a fundamental difference: the HyperLink control only navigates to the target URL, while the LinkButton control posts the form and, if the event handler chooses, navigates to the target URL.

The HyperLink control has four specific attributes:

ImageUrl: The path to an image (rather than text) to display. If this attribute is used, the control appears to the user as identical to an ImageButton control, although the ImageButton control still posts the form and the HyperLink control only navigates.
NavigateUrl: The target URL to navigate to.
Text: The text string that will be displayed on the browser as the link. If both the Text and ImageUrl properties are set, the ImageUrl takes precedence. The text is displayed if the image is unavailable.

If the browser supports tool tips and the ToolTip property has not been set, then the Text value will display as a tool tip. If the ToolTip property has been set, then the ToolTip text string will display as a tool tip.

Target: Defines the target window or frame that will load the linked page. The value is case insensitive and must begin with a character in the range of a to z, except for the special values shown in Table 5-3, all of which begin with an underscore.

Table 5-3. Special values of the Target attribute
Value	Description
`_blank`	Renders the content in a new unnamed window without frames.
`_new`	Not documented, but behaves the same as `_blank`.
`_parent`	Renders the content in the parent window or frameset of the window or frame with the hyperlink. If the child container is a window or top-level frame, it behaves the same as `_self`.
`_self`	Renders the content in the current frame or window with focus. This is the default value.
`_top`	Renders the content in the current full window without frames.

Example 5-8 and Example 5-9 demonstrate a hyperlink in C# and VB.NET, respectively.

Example 5-8. HyperLink in C#, csASPHyperLink.aspx

<%@ Page Language="C#" %>  <html>    <body>    <form runat="server">       <h1>ASP Controls</h1>       <h2>HyperLink</h2>       <asp:hyperLink                    NavigateUrl="//localhost/progaspnet/TargetPage.aspx"          Text="HyperLink to Target Page"           target="_self"          Font-Name="Impact"          Font-Size="16pt"          toolTip="Click here to go to Target Page."          runat="server" />    </form>    </body> </html>

Example 5-9. HyperLink in VB.NET, vbASPHyperLink.aspx

<%@ Page Language="VB" %> <html>    <body>    <form runat="server">       <h1>ASP Controls</h1>       <h2>HyperLink</h2>       <asp:hyperLink                    NavigateUrl="//localhost/progaspnet/TargetPage.aspx"          Text="HyperLink to Target Page"           target="_self"          Font-Name="Impact"          Font-Size="16pt"          toolTip="Click here to go to Target Page."          runat="server" />    </form>    </body> </html>

The result of running Example 5-8 or Example 5-9 is shown in Figure 5-4.

Figure 5-4. HyperLink control

The HyperLink control is rendered on the client browser as an HTML anchor tag (that is, <a>). You can verify this by examining the source code for the web page on your browser.

Table 5-3. Special values of the Target attribute

Example 5-8. HyperLink in C#, csASPHyperLink.aspx

Example 5-9. HyperLink in VB.NET, vbASPHyperLink.aspx

Figure 5-4. HyperLink control