Tag Archives: JQuery

Get Querystring With jQuery – Darlesson Oliveira

Get Querystring With jQuery – Darlesson Oliveira.

ASP.NET–prevent button from form submit based on condition in javascript

Here is a javascript function that retutns true or false based on wheather a listbox is empty (select element in html does not have any option elements)

function WarnIfCleanersListboxEmpty() {
    if ($('#lboxCleaners').children().length == 0) {
        alert('list is empty');
        return false;
    return true;

in ASP.NET page there is a button that submits the form

 <asp:Button ID="btnGenerate" runat="server" Text="Generuj" OnClientClick="return WarnIfCleanersListboxEmpty()"/>

it’s the return in OnClientClick that I always forget and then wander why the form gets submitted even if my javascript function evaluates to false.

WRONG: OnClientClick=”WarnIfCleanersListboxEmpty()”

RIGHT: OnClientClick=”return WarnIfCleanersListboxEmpty()”


Scripts, tools and tips, mostly around Microsoft SCCM and EMS

To The Point

Anything about Technology and Business

Brian's Power Windows Blog

Microsoft in the Enterprise. Windows, Hyper-V, Exchange, SQL, and more!

PowerScripting Podcast

Shownotes and links for the PowerScripting Podcast, a podcast to help people learn Windows Powershell

Learn Powershell | Achieve More

What is this Powershell of which you speak?