doing exercises on the creation and insertion of dynamic elements while watching the sharp jQuery
<ul id="ul">
<li title=""></li>
<li title=""></li>
<li title=""></li>
</ul> $("html"); // dom
//li
var $li_1 = $("<li></li>");
//li
var $li_2 = $("<li><li>");
// li
var $li_3 = $("<li tltle = ""><li>");
//
// append()
$ul.append($li_1).append($li_2).append($li_3);
as a result, it is found that the empty li tag is repeated many times
