("#id").css('display','none');
$("#id").css('display','block');
or
$("#id")[0].style.display = 'none';
$("#id") returns JQuery
It is a collection and must have a display attribute
$("#id").show() means display:block, $("#id").hide() means display:none; $("#id").toggle() switches the visibility of the element state. If the element is visible, switch to hidden; if the element is hidden, switch to visible