The Data Preview is an advanced tool that will allow you to view the current state of your form data as you perform form entry. This can be found on Web Apps and on App Preview. You can view either the XML structure itself with values filled in, or the questions in a clearer user interface. Additionally, you can enter XPath's to see how they evaluate against the current XML form structure.
This feature is only available to users with edit_data permissions.
Form entry is performed as usual and you will notice a bar at the bottom of the page that says Data Preview. This can also be found on theicon in App Preview.
To open data preview, simply click the dark blue bar at the bottom to open it. Below you'll see a screen with the form data shown. This is useful for figuring out calculations on hidden values without submitting the form to the server.
The debugger is also available in live preview. You can access it when you are in a form. Look for a data table icon in the bottom right.
In most scenarios, viewing just the form data is enough to get insight on your application. However, Data Preview also offers the ability to query your data as well as view the raw xml of the form.
The Evaluate XPath tab allows users to evaluate arbitrary XPath clauses on their data. This is useful to test different conditions or expressions with the form in the current state. Note: you need to use /data/... syntax rather than the #form/... syntax as you would in Formbuilder!
In other cases, you may desire to see the actual form XML that is being generated by the form. You can do this by selecting the Form XML tab.