.NET Framework Class Library
PageSetFocus Method (String)

Sets the browser focus to the control with the specified identifier.

Namespace:   System.Web.UI
Assembly:  System.Web (in System.Web.dll)
Syntax
Public Sub SetFocus ( _
	clientID As [%$TOPIC/cssff821_en-us_VS_110_1_0_0_0_0%] _
)
public void SetFocus(
	[%$TOPIC/cssff821_en-us_VS_110_1_0_1_0_0%] clientID
)
public:
void SetFocus(
	[%$TOPIC/cssff821_en-us_VS_110_1_0_2_0_0%]^ clientID
)
member SetFocus : 
        clientID:[%$TOPIC/cssff821_en-us_VS_110_1_0_3_0_0%] -> unit

Parameters

clientID
Type: SystemString

The ID of the control to set focus to.

Exceptions
ExceptionCondition
ArgumentNullException

clientID is .

InvalidOperationException

SetFocus is called when the control is not part of a Web Forms page.

- or -

SetFocus is called after the PreRender event.

Remarks

Use the SetFocus method to make the control with the specified ID string the active control in the Web page displayed by the browser. The SetFocus method must be called before the page is prepared for rendering to the client in the PreRender event.

NoteNote

The SetFocus method will work only on browsers supporting ECMAScript version 1.3 or later.

Examples

The following code example sets the focus to the second text box on a Web page.

Security noteSecurity Note

This example has a text box that accepts user input, which is a potential security threat. By default, ASP.NET Web pages validate that user input does not include script or HTML elements. For more information, see Script Exploits Overview.

<%@ page language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
    Sub Page_Init(ByVal sender As Object, ByVal e As EventArgs)
        SetFocus(focusHere.ClientID)
    End Sub
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">
        <asp:textbox id="default" runat="server" /><br />
        <asp:textbox id="focusHere" runat="server" />
    </form>
</body>
</html>
<%@ page language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
    void Page_Init(object sender, EventArgs e)
    {
        SetFocus(focusHere.ClientID);
    }
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
    <title>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">
        <asp:textbox id="default" runat="server" /><br />
        <asp:textbox id="focusHere" runat="server" />
    </form>
</body>
</html>
Version Information

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0
Platforms

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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