How to create a Pop Ups

You already have the code for the popup itself then you can easily wrap it as a plugin and use the "dashboardLoaded" event to trigger that functionality on all dashboards. 

 

If you need it to happen only on specific dashboards that you can add another configuration file on the server and then write your logic around it so it will be something like: 

var PopupEnabledDashboard = [DASH_ID1, DASH_ID2];