Get JSON of specific gjs-data-type

I want to export JSON of only a specific gjs-data-type="img" I'm trying this but it doesn't give any result:

id: "show-json",
          className: "btn-show-json",
          label: "JSON",
          context: "show-json",
          command(editor) {
            editor.Modal.setTitle("Components JSON")
              .setContent(
                `<textarea style="width:100%; height: 500px;">
            ${JSON.stringify(editor.getType('img')}
          </textarea>`
              )
              .open();
          }