Class Range

// Bold all selected text. const selection = DocumentApp.getActiveDocument().getSelection(); if (selection) {   const elements = selection.getRangeElements();   for (let i = 0; i < elements.length; i++) {     const element = elements[i];      // Only modify elements that can be edited as text; skip images and other     // non-text elements.     if (element.getElement().editAsText) {       const text = element.getElement().editAsText();        // Bold the selected part of the element, or the full element if it's       // completely selected.       if (element.isPartial()) {         text.setBold(             element.getStartOffset(),             element.getEndOffsetInclusive(),             true,         );       } else {         text.setBold(true);       }     }   } }