隐藏ul出有关问题

function onClickul(target) {

            var ul = document.getElementById(target).getElementsByTagName('ul');            

            for (var i = 0; i < ul.length; i++) {

                if (ul[i].style.diplay != "none") {

                    ul[i].style.diplay = "none";

                }

                else {

                    ul[i].style.diplay = "";

                }

            }

        }