Now that the user has selected a sheet, we want to change the UI that is displayed and populate a data grid with the data for the selected marks, or a message indicating no marks are selected. We also set up some other UI components, such as hooking up a button for switching which sheet to get data from.
Once the right UI is showing, we need to ask Tableau for the data of the sheet the user picked. The first step is to find the worksheet object by name inside the tableau.extensions.dashboardContent.dashboard.worksheets array. After we have the sheet, we call the worksheet.getSelectedMarksAsync() API to get the data for the marks that are selected. This is an asynchronous call which returns a promise. We can consult the Extensions API documentation to find out what format the returned data will have.
The final step is to process the returned data into a format that Data Tables expects and pass the data over. We do this by mapping the data into rows and column headers before initializing the data table component. DataTables has great documentation, so we won't go into details about how we configured the table.
