Question

I’d like to have ability to hover on one div to affect another.

<div id="a">1</div>
<div id="b" style="display:none;">2</div>

How to hover #a and make #b appear?
I’d like a css3 solution but jquery also is good.

Answer 1

$("#a").on({
     mouseenter: function() {
         $("#b").show();
     },
     mouseleave: function() {
         $("#b").hide();
     },
     click: function() {
         alert('Holy crap! Someone clicked me!');
     }
});

If you place #b inside #a, you could do it with CSS, otherwise the jQuery solution above should work (with jQuery 1.7+).