jQuery - как надо, и как не надо

jquery.howto.md

Getting first element

Wrong way

var first = $(list.get(0));

Right way

var first = list.first();

Using same element several times

Wrong way

$('selector').find("a").dosomething();
$('selector').find(".b").dosomethingmore();

Right way

var node = $('selector');
node.find("a").dosomething();
node.find(".b").dosomethingmore();