You can do this in VBScript.
<script language="VBScript">
myPrompt = MsgBox("Are you sure you want to delete?",3,"Important Question")
</script>
Variable myPrompt will contain 6 for yes, 7 for no an 2 for cancel.
Unfortunately, javascript does not provide a configurable alert box.
You could alternatively use a html popup like the following which I found somewhere. Just need to edit it to your taste:
<html>
<head>
<title>Confirm-box</title>
</head>
<body>
<SCRIPT LANGUAGE="JavaScript">
<!--
var winConfirm = null;
function showConfirm()
{
var windowWidth = 250;
var windowHeight = 100;
var locX = ( screen.width - windowWidth ) / 2;
var locY = ( screen.height - windowHeight ) / 2;
var windowFeatures = "width=" + windowWidth + ",height=" + windowHeight +
",screenX=" + locX + ",screenY=" + locY + ",left=" + locX + ",top=" + locY;
if ( ( winConfirm != null ) && !winConfirm.closed )
{
winConfirm.close();
}
winConfirm = open( "", "winConfirm", windowFeatures );
var theHTML = '<HEAD><TITLE>Please choose...</TITLE></HEAD>'
+ '<BODY BGCOLOR="#FFFFFF">'
+ '<CENTER><B>'
+ 'Click on YES, NO or CANCEL'
+ '</B><FORM NAME="buttonForm">'
+ '<INPUT TYPE="button" VALUE=" YES "'
+ ' ONCLICK="opener.buttonClicked(0);self.close();">'
+ ' '
+ '<INPUT TYPE="button" VALUE=" NO "'
+ ' ONCLICK="opener.buttonClicked(1);self.close();">'
+ ' '
+ '<INPUT TYPE="button" VALUE="CANCEL"'
+ ' ONCLICK="opener.buttonClicked(2);self.close();">'
+ '</FORM></BODY>';
winConfirm.document.writeln( theHTML );
}
function buttonClicked( buttonChoice )
{
switch( buttonChoice )
{
case 0:
document.myForm.showResult.value = "YES";
break;
case 1:
document.myForm.showResult.value = "NO";
break;
case 2:
document.myForm.showResult.value = "CANCEL";
break;
default:
document.myForm.showResult.value = "(void)";
}
}
//-->
</SCRIPT>
<FORM NAME="myForm">
<INPUT TYPE="button" VALUE="Click here to see the confirm window"
ONCLICK="showConfirm();">
<BR><BR><B>The last button clicked was:</B>
<BR><INPUT NAME="showResult" TYPE="text" SIZE="10" VALUE="(void)"
ONFOCUS="blur();">
</FORM>
</body>
</html>