how to keep web page displayed during JavaScript alert in Chrome & FireFox for a VB ASP.NET web app

Question

Is there a way to keep page displayed in background while alert popup is displayed? (IE keeps it displayed)

In my VB ASP.NET web app, I popup an alert by using JavaScript alert(). (see code below) But when alert pops up, Chrome and FF web page goes blank until user hits OK, then it is re-displayed. (IE doesn't have problem)

' Shows javascript alert_message at browser, because MsgBox doesn't work there.
Private Sub alert(ByVal alert_message As String)
    Dim msg As String
    msg = "<script language='javascript'>"

    msg += "alert('" & POPUP_ALERT_TITLE & "\n\n" & alert_message & "');"

    msg += "<" & "/script>"
    Response.Write(msg)
End Sub

SAMPLE USAGE WITHIN MY VISUAL BASIC 2013 ASP.NET WEB APP..........

Function sample_usage()
    alert("INTERNAL ERROR 111.")
End Function

Answer 1

Javascript executes on a single thread. Alert boxes interrupt that thread, causing it to hang until the user closes it. See this jsFiddle for an example.

<div id="messages">
</div>

<script>
alert('test');
$('#messages').text( 'alert is done!' );
</script>

What's likely happening is that you have some Javascript which is reloading portions of the page. IE is executing things in a particular order, and Chrome and Firefox are doing things in a slightly different order (or are doing things faster/slower). So in IE, the page underneath has finished (or not started) loading/reloading while in Chrome and Firefox the page is in the middle of loading/reloading.

Unfortunately, there's no simple solution to this... any answer will involve changing your Javascript a bit. I'd recommend using something like blockUI and then showing things like alerts after a timeout (to give other parts of your Javascript a chance to finish).

Answer 2

您也可以这样写：

Response.write("<script type=""text/javascript"">setTimeout(function(){alert("" type your message here"")},100);</script>")

Answer 3

This fixed it:

Private Sub alert(ByVal alert_message As String)
    Dim msg As String
    msg = "<script language='javascript'>"

    ' The 100 ms delay prevents a blank page during alert, in Chrome and FireFox:
    msg += "setTimeout(function(){alert('" & POPUP_ALERT_TITLE & "\n\n" & alert_message & "')}, 100);"

    msg += "<" & "/script>"
    Response.Write(msg)
End Sub