Explore / loop through Gliderecord returned object (keys, array)

gr_keys_array_loop.js

var source = new GlideRecord('u_pentest_import_api');
  source.addEncodedQuery('sys_import_row=0^ORsys_import_row=NULL');
  source.query();
  while(source.next()){
      keys = Object.keys(source);
      for (i=0; i < keys.length; i++) {
        gs.info(keys[i] + "::" +source[keys[i]]);
      }

  }