gistfile1.txt

    var targetUsername = 'ccc';
    var jsons = $("#downloaded").val().split("\n");
    jsons = $.map(jsons, function (json, i) {
      json = JSON.parse(json);
      if (json.username === targetUsername) {
        return {"key": json.username, "count": 1, "like": json.like}
      } else {
        return null;
      }
    });
    (function (values) {
      var result = {"count": 0, "like": 0};
      for (var i in values) {
        result.count += values[i].count;
        result.like += values[i].like;
      }
      $('#output').val("targetUsername: " + targetUsername + "\ncount: " + result.count + "\nlike:" + result.like);
    })(jsons);