I've been working on trying to set the focus of client side controls today and thought I'd submit this as I think it could be useful. I hope I haven't missed a method that is already built into ASP.NET that already does this.
I've created a helper class that enables you to set the client side focus
with a single call. I decided against creating a subclass of the Page class
as I think the helper class approach is better and easier to implement
on existing systems.
All that is required is the ID of the form which the control is in and the ID of the control itself. There are a couple of overloaded functions that automatically find these IDs depending on what type of server control you pass as a parameter.
private void Page_Load(object sender, System.EventArgs e)
{
if( !this.IsPostBack )
{
McGiv.Web.UI.ClientSideFocus.setFocus(this.TextBox1);
this.ViewState["focus"] = "WebControl";
}
}
The JavaScript script is then generated and registered to the given Page object.
The script itself makes a copy of the document.body.onload function and
replaces it with the focus setting function which in turn calls the original
onload function, which means that you won't have to tinker with any existing
onload scripts you may have within your pages.
// save original function
if(document.body.onload)
original = document.body.onload;
// override original function
document.body.onload = document_onLoad;
function document_onLoad()
{
try
{
document.FormID.ControlID.focus();
}
catch(e){}
// call original function
original();
}
function original()
{
// do nothing if original is null
}
After being notified that the original code could potentially steal
the focus of another window (which can be irritating), I switched from
using the document.body.onload event to the document.body.onfocus event.
var called = false;
if(document.body.onfocus)
orig_document_body_onfocus = document.body.onfocus;
document.body.onfocus = document_body_onfocus;
function setFocus()
{
var control = document.getElementById("html");
if(control)
control.focus();
}
function orig_document_body_onfocus(){}
function document_body_onfocus ()
{
if( !called )
{
called = true;
setFocus();
}
orig_document_body_onfocus();
}
if( window.__smartNav && window.__smartNav.restoreFocus)
{
orig_window__smartNav_restoreFocus = window.__smartNav.restoreFocus;
window.__smartNav.restoreFocus = window__smartNav_restoreFocus;
}
function orig_window__smartNav_restoreFocus(){}
function window__smartNav_restoreFocus()
{
setFocus();
orig_window__smartNav_restoreFocus
}
I�ve also tried to solve the problem with Smart Navigation by overriding
the restoreFocus function from within SmartNav.js file but this seems to only
work on my local machine at the moment. This may be due to a security issue
or due to the loading time taken from remote hosts.
I removed the need for the ID of the HTML form, as with most cases within ASP.NET, the page will only use one form. This modification alone removes about half the content from the original code. I�ve included the original code if you still need to reference the form's ID as well as the control ID.
Currently, the helper class doesn�t function properly when Smart Navigation is enabled.
I've included a simple demo that switches focus between a WebControl,
HtmlControl and a hard coded HTML input control.
I use the viewstate to keep track of which control has focus.
private void Button1_Click(object sender, System.EventArgs e)
{
string focus = this.ViewState["focus"] as string;
if( focus == null )
focus = "WebControl";
switch(focus)
{
case "Html":
{
McGiv.Web.UI.ClientSideFocus.setFocus(this.TextBox1);
this.ViewState["focus"] = "WebControl";
break;
}
case "HtmlControl":
{
McGiv.Web.UI.ClientSideFocus.setFocus(this, "html");
this.ViewState["focus"] = "Html";
break;
}
case "WebControl":
{
McGiv.Web.UI.ClientSideFocus.setFocus(this.HtmlControl1);
this.ViewState["focus"] = "HtmlControl";
break;
}
}
}
In order to get it to work, unzip the demo files into a virtual directory mapped to http://localhost/ClientSideFocus/.
I've also setup an online demo here.
Enjoy.
setFocus from the document.body.onload event to
the document.body.onfocus event. This stops the focus being taken from
another browser window that has the focus.
onload event. Allows it to work with Mozilla browsers too.
getElementById([control name]) instead of using [form name].[control name].
restoreFocus Smart Navigation function.
Now works when smart navigation is enabled.
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