Question

getting an error on my jQuery code. Tried without noConflict, not resolving the issue.
The jQuery files exist in the location, in fact it used to work and all of a sudden it didn’t. I reverted back to the previous version of the code, but the same error remains:

<link href="/_layouts/project/jQuery/jquery-ui-1.8.18.custom.css"rel="stylesheet" type="text/css" />
<script src="/_layouts/project/jQuery/jquery-1.7.1.js"></script>

<script src="/_layouts/project/jQuery/jquery-ui-1.8.18.custom.min.js"></script>
<script type="text/javascript">
    function openDialog() {
        var options = {
            url: "selectservices.aspx",
            autoSize: true,
            allowMaximize: true,
            title: "My PopUp",
            showClose: true,
            dialogReturnValueCallback: onClose
        };
        SP.UI.ModalDialog.showModalDialog(options);
    }
    function onClose(dialogResult, returnValue) {
        SP.UI.ModalDialog.RefreshPage(SP.UI.DialogResult.OK);
    }
</script>
<script>
    $(document).ready(function () {
        $("#tabs").tabs(); 
    });
</script>

Answer 1

Are you absolutely sure that the jQuery and jQuery UI files are getting loaded into the page? Do a debug, and check that jQuery and jQuery.ui are defined in your pages.

If they are, then something is wrong. Maybe your custom jQuery UI JS file does not have the Tabs component baked in. You may have neglected to include it in your customization prior.