Which statement best describes the communication mechanism used by block widgets?

• A. True
• B. False
• C. Not applicable
• D. Not supported

Answer: (A)

Block widgets rely on a message-passing channel to talk with the hosting editor, usually using the window.postMessage API to send and receive events between the widget’s iframe and the parent page. This design keeps the widget sandboxed and secure while still enabling dynamic exchanges like configuration data, content updates, and commands. Because the widget runs in isolation, it can’t directly access the editor’s DOM; messaging is the safe, standard way to communicate across the boundary. So stating that the communication is based on this message-based mechanism is the correct characterization. The other options imply there is no communication or no supported mechanism, which doesn’t reflect how block widgets actually interact with the editor.