subsort by a second thing in TypeScript

Just chase the first pair of return conditions with a second pair of return conditions.

public sortByRowDataLength(data): CircleTimelineDataModel {
   return data.headers.sort((yin, yang) => {
      if (yin.rowData.length < yang.rowData.length) {
         return 1;
      }
      if (yin.rowData.length > yang.rowData.length) {
         return -1;
      }
      if (yin.label > yang.label) {
         return 1;
      }
      if (yin.label < yang.label) {
         return -1;
      }
      return 0;
   });
}