exportTML({
  metadata: [
    {
      type: "LIVEBOARD", //Metadata Type
      identifier: "9bd202f5-d431-44bf-9a07-b4f7be372125" //Metadata Id
    }
  ],
  export_associated: false,//indicates whether to export associated metadata objects
  export_fqn: false, //Adds FQNs of the referenced objects.For example, if you are
                     //exporting a Liveboard and its associated objects, the API
                     //returns the Liveboard TML data with the FQNs of the referenced
                     //worksheet. If the exported TML data includes FQNs, you don't need
                     //to manually add FQNs of the referenced objects during TML import.
  edoc_format: "JSON" //It takes JSON or YAML value
}).then(result => {
  console.log(result);
}).catch(error => {
  console.error(error);
});