Cannot read property of undefined, aj keď je definovaný

function objekt(){
  this.list = {};

  this.vytvorElement = function(){
    var el = document.createElement("div");
    el.id = "el1";
    document.body.appendChild(el);
    this.list.element = document.getElementById("el1");
  }

  this.citajElement = function(e){
    var el = this.list.element;
  }
}

var obj = new objekt;
obj.vytvorElement(); // div sa vytvori, vlozi sa do body, vsetko OK
obj.citajElement(); // Cannot read property "element" of undefined

function player(){
  this.playlist = null;
  this.el = {};

  this.create = function(){
    if(!document.getElementById("player")){
      var main = document.createElement("div");
      main.id = "player";
      main.style.top = "-100%";
      document.body.appendChild(main);
      this.el.main = document.getElementById("player");

      var playlist = document.createElement("div");
      playlist.id = "playlist";
      playlist.style.left = "-25%";
      this.el.main.appendChild(playlist);
      this.el.playlist = document.getElementById("playlist");

      // ... kopa dalsich createElement...
    }
  }

  this.show = function(){
    if(this.el.main && this.el.main.style.top == "0%"){
      this.el.main.style.top = "-100%";
    }else{
      this.el.main.style.top = "0%";
    }
  }

  this.togglePlaylist = function(e){
    var playlist = this.el.playlist; // tu nastane chyba Cannot read property...
    var player = this.el.player;
    var button = e.target;
    if(playlist.style.left != "0%"){
      playlist.style.left = "0%";
      player.style.margin = "0 1% 0 26%";
      button.className = "hide";
    }else{
      playlist.style.left = "-25%"
      player.style.margin = "0 5%";
      button.className = "";
    }
  }
}