Keypress event in ASP.NET

In VB this is my code on having only numeric input on the textbox.

Private Sub txtbox_KeyPress(Index As Integer, KeyAscii As Integer)
If Index = 5 Or Index = 6 Or Index = 7 Then
Select Case KeyAscii
Case vbKey0 To vbKey9
Case vbKeyDelete
Case vbKeyBack
Case Else
KeyAscii = 0
End Select
End If
End Sub

How can I do this in my ASPX page?
Thanks

The only way I know of is to use an HTML TextField instead of a Web Forms TextBox and use JavaScript.

The HTML element would look like:

PHP Code:

---

<INPUT onkeypress="return KeyCheck(this, event);" id="txtTest" type="text"> 


---

and the JavaScript:

PHP Code:

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function KeyCheck(myField, e)
{
    var key;
    
    if (window.event)
        key = window.event.keyCode;
    else if(e)
        key = e.which;
    else 
        return true;
        
    if (((key > 47) && (key < 58)) || (key == 8))
        return true;
    else 
        return false;
} 


---

thanks this really works