checkbox problem

[PJ6]

OnPreRender if I add this...

Me.Attributes.Add("onmousedown", "alert(this.checked)")

I get 'undefined', at least in IE. Everywhere I look "checked" is supposed
to be the property to retreive the value of a checkbox... obviously I've
missed something. Someone want to give me a clue?

Thanks,
Paul

 

[Paul Henderson]

Everywhere I look "checked" is supposed

to be the property to retreive the value of a checkbox... obviously I've
missed something. Someone want to give me a clue?

'checked' is the correct property, and should work on any version of IE

3. It might help if you posted a bit more of the relevant source code [and also check the HTML from 'View Source']. Also, see what 'this' is set to - if it's undefined itself, then IE is probably being silly; you could try something like getElementByID(...) to get a reference to the object. But 'this' should work...

 

[S. Justin Gengo [MCP]]

Paul,

Is this a checkbox list or a single checkbox?

If it's a list then you have to specify which item in the list to check.
Another difficulty is the way .NET renders the list using columns. Here's a
script I wrote as part of a CheckBoxList Validator I created:

Dim StringBuilder As New Text.StringBuilder
StringBuilder.Append("<script language=""javascript"">" &
vbCrLf)
StringBuilder.Append("<!--" & vbCrLf)
StringBuilder.Append("function
checkboxlist_verification(clientID) {" & vbCrLf)
StringBuilder.Append("var val =
document.all[document.all[clientID].controltovalidate];" & vbCrLf)
StringBuilder.Append("var col = val.all;" & vbCrLf)
StringBuilder.Append("if (col != null ) {" & vbCrLf)
StringBuilder.Append("var checked = 0;" & vbCrLf)
StringBuilder.Append("var checkboxcount = 0;" & vbCrLf)
StringBuilder.Append("for (i = 0; i < col.length; i++ ) {" &
vbCrLf)
StringBuilder.Append("if (col.item(i).tagName == 'INPUT') {"
& vbCrLf)
StringBuilder.Append("checkboxcount += 1;" & vbCrLf)
StringBuilder.Append("if (col.item(i).checked ) {" & vbCrLf)
StringBuilder.Append("checked += 1;" & vbCrLf)
StringBuilder.Append("if (checked == " &
NumberOfCheckBoxesRequired & ") {" & vbCrLf)
StringBuilder.Append("return true;" & vbCrLf)
StringBuilder.Append("}" & vbCrLf)
StringBuilder.Append("}" & vbCrLf)
StringBuilder.Append("}" & vbCrLf)
StringBuilder.Append("}" & vbCrLf)
StringBuilder.Append("if (checked == checkboxcount) {" &
vbCrLf)
StringBuilder.Append("return true;" & vbCrLf)
StringBuilder.Append("};" & vbCrLf)
StringBuilder.Append("else {" & vbCrLf)
StringBuilder.Append("return false;" & vbCrLf)
StringBuilder.Append("}" & vbCrLf)
StringBuilder.Append("}" & vbCrLf)
StringBuilder.Append("}" & vbCrLf)
StringBuilder.Append("-->" & vbCrLf)
StringBuilder.Append("</script>" & vbCrLf)

ClientScriptManager.RegisterClientScriptBlock(ScriptType,
"CheckBoxListVerification", StringBuilder.ToString())

The component I created lets you specify how many checkboxes in a
checkboxlist must be checked for the page to validate. If that's what you
happen to be attempting you may download the component which is free and
includes all source code from here:

http://www.aboutfortunate.com/default.aspx?page=checkboxlistvalidatordemo


--
Sincerely,

S. Justin Gengo, MCP
Web Developer / Programmer

www.aboutfortunate.com

"Out of chaos comes order."
Nietzsche

 

[PJ6]

I'll be damned but this morning it's working as expected. Yesterday it was
giving me 'undefined'. I have no idea why, probably my fault, something
dumb. Par for the course.

Paul

--------
Public Class TestControl
Inherits CheckBox

Public Sub New()
Me.Text = "1234"
End Sub

Protected Overrides Sub OnPreRender(ByVal e As System.EventArgs)
Me.Attributes.Add("onclick", "alert(this.checked)")
MyBase.OnPreRender(e)
End Sub

End Class