Class Selection

const selection = SlidesApp.getActivePresentation().getSelection();
const currentPage = selection.getCurrentPage();
if (currentPage != null) {
  Logger.log(`Selected current active page ID: ${currentPage.getObjectId()}`);
}

const selection = SlidesApp.getActivePresentation().getSelection();
const selectionType = selection.getSelectionType();
if (selectionType === SlidesApp.SelectionType.PAGE_ELEMENT) {
  const currentPage = selection.getCurrentPage();
  const pageElements = selection.getPageElementRange().getPageElements();
  Logger.log(`Number of page elements selected: ${pageElements.length}`);
}

const selection = SlidesApp.getActivePresentation().getSelection();
const selectionType = selection.getSelectionType();
if (selectionType === SlidesApp.SelectionType.PAGE) {
  const pageRange = selection.getPageRange();
  Logger.log(
      `Number of pages in the flimstrip selected: ${
          pageRange.getPages().length}`,
  );
}

const selection = SlidesApp.getActivePresentation().getSelection();
const selectionType = selection.getSelectionType();
if (selectionType === SlidesApp.SelectionType.CURRENT_PAGE) {
  const currentPage = selection.getCurrentPage();
  Logger.log(`Selected current active page ID: ${currentPage.getObjectId()}`);
}

const selection = SlidesApp.getActivePresentation().getSelection();
const selectionType = selection.getSelectionType();
if (selectionType === SlidesApp.SelectionType.TABLE_CELL) {
  const currentPage = selection.getCurrentPage();
  const tableCells = selection.getTableCellRange().getTableCells();
  const table = tableCells[0].getParentTable();
  Logger.log(`Number of table cells selected: ${tableCells.length}`);
}

const selection = SlidesApp.getActivePresentation().getSelection();
const selectionType = selection.getSelectionType();
if (selectionType === SlidesApp.SelectionType.TEXT) {
  const currentPage = selection.getCurrentPage();
  const pageElement = selection.getPageElementRange().getPageElements()[0];
  const textRange = selection.getTextRange();
  Logger.log(`Text selected: ${textRange.asString()}`);
}