Use the XSL Transformation Output view
The XSL Transformation Output view displays the output of the XSL transformation as you debug. As you are debugging, the view updates when the debugger suspends execution.
You can set the view to display a text rendering of the output or a browser rendering of the output. To have the view display text, click the Text View button or choose the view's down arrow menu and select Text View. To have the output display in a browser, click the Browser View button or choose the view's down arrow menu and select Browser View.
Note: If the current state of the output is not well-formed XML, the browser view will not be able to display the XML.
If there are multiple transform output files during a debug session, they will display as separate tabs in the view.