Q:

js/css add multiple backgrounds

i have seen several usages of the .css() function or simply setting element.style.background in js
what i want is to stack multiple backgrounds, ie add another background over the 1st one.
i tried 
input.style.background.add("white url('http://cssdeck.com/uploads/media/items/5/5JuDgOa.png') no-repeat 30px 6px;");

but the add function is not recognized : 

TypeError: input.style.background.add is not a function

i guess i could set the css after onload with "background1", then reset it as "background1, background2" and back to "background1" when i need to but i would prefer an add() / remove() approach

A:

why not create a few classes : 
.bg-1{bg-img ...1}
.bg-2{bg-img ...2}

and use 
.addClass('bg-1');

and
.removeClass('bg-x');

etc... with a js function with the wanted delay
Warning : 
Jquery functions apply to jquery objects, for you :
$(input).addClass('some-class');

