JavaScript getElementById for ASP.NET Control returns null?

asp.net, getelementbyid, javascript, webforms

Solution

This:

function ConfirmTransfere() {
        if (confirm("Syatem not allow negative inventory, would you like to continue ?") == true) {
            document.getElementById("btnAlelrt").click();

        }

needs to be this:

function ConfirmTransfere() {
        if (confirm("Syatem not allow negative inventory, would you like to continue ?") == true) {
            document.getElementById('<%=btnAlert.ClientID%>').click();

        }

The problem is that your button is an ASP.Net control and will generate it's own client id, which will be different from the ID you specified. putting in the code `<%=btnAlert.ClientID%>` Will post the generated one out to the browser.

Problem

I use JavaScript and this error appears for me during execution: ``` Microsoft JScript runtime error: 'document.getElementById(...)' is null or not an object ``` this my code: ``` <asp:Content ID="content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server"> <script language="javascript" type="text/javascript"> function ConfirmTransfere() { if (confirm("Syatem not allow negative inventory, would you like to continue ?") == true) { document.getElementById("btnAlelrt").click(); } } </script> <asp:ScriptManager ID="ScriptManager1" runat="server"> </asp:ScriptManager> <asp:UpdatePanel ID="uxContainer" runat="server"> <ContentTemplate> <table> <tr> <td> <asp:Button ID="uxTransfer" runat="server" Text="Transfer" OnClick="uxTransfer_Click" /> <asp:Button ID="btnAlelrt" runat="server" Text="GetDetails" OnClick="btnAlelrt_Click" /> </td> </tr> </table> </ContentTemplate> <Triggers> <asp:PostBackTrigger ControlID="uxTransfer" /> </Triggers> </asp:UpdatePanel> </asp:Content> ```

Original source