网页代码怎么实现上下划动，用户没选择的时候显示不限

'

怎么实现自动选择，不限， var itHousePicker = new $.PopPicker();
itHousePicker.setData([{
text: '不限'
},{
text: '高'
}, {
text: '一般'
}, {
text: '低'

                    }]);
                var showItHousePickerButton = doc.getElementById('itHouse');

                showItHousePickerButton.addEventListener('tap', function(event) {
                    var that=this;
                    itHousePicker.show(function(items) {
                        that.innerHTML = items[0].text

                    });
                }, false);

你这能描述清楚点么？是一个选择初始化问题？