jQuery

• Prefix jQuery object variables with a $.

// bad
const sidebar = $('.sidebar');

// good
const $sidebar = $('.sidebar');

// good
const $sidebarBtn = $('.sidebar-btn');

• Use find with scoped jQuery object queries.

// bad
$('ul', '.sidebar').hide();
$('.sidebar').find('ul').hide();
$('.sidebar').children('ul').hide();

// good
$('.sidebar ul').hide();
$('.sidebar > ul').hide();
$sidebar.find('ul').hide();