SharePoint Status Notifications and Pop Ups SharePoint 2013 Apps

First we need to refer following SharePoint related JavaScript and jQuery

<script type="text/javascript" src="YourLocation/Scripts/jquery-2.0.1.min.js"></script>

<script type="text/javascript" src="/_layouts/15/MicrosoftAjax.js"></script>

<script type="text/javascript" src="/_layouts/15/sp.runtime.js"></script>

<script type="text/javascript" src="/_layouts/15/sp.js"></script>

After That You can

<script language="javascript" type="text/javascript">

    // This will automatically disappear after some time

    SP.UI.Notify.addNotification('Processing...', false);

    // This will remove after you click or removed by a code

    SP.UI.Notify.addNotification('Processing...', true);

</script>

<script language="javascript" type="text/javascript">

// Set the status and get the reference

var status = SP.UI.Status.addStatus("Info:", "Processed");

// Add a Color

SP.UI.Status.setStatusPriColor(status, 'blue');

//Set Time out time , If not It will be there until we click

setTimeout(function () { SP.UI.Status.removeStatus(status); },3000);

</script>

Few other Methods we can use

<script language="javascript" type="text/javascript">

    // Remove Specific status

    SP.UI.Status.removeStatus(status);

    // Remove All status

    SP.UI.Status.removeAllStatus(true);

</script>