A single-page application (SPA) is a web application that retrieves all the necessary code — HTML, JavaScript, and CSS — with a single page load or else dynamically loads necessary resources and adds them to the page as needed. The page does not reload, nor does control transfer to another page. With a single-page application, all elements of the Document Object Model exist in one page. This differs from a traditional web application because the SPA page reloads differently and all objects in the application can exist in the DOM simultaneously. When interrogating single-page applications, you must define the container controls to house the application's controls in order to match correctly. Container controls are parents of the other controls. 

NOTE: It is not recommended to incorporate and interrogate Pega applications in a robotic solution. This is only used as an example. Please review the documentation on Community: https://community.pega.com/knowledgebase/documents/working-single-page-web-applications