Add the previous set of elements on the stack to the current set, optionally filtered by a selector.
Optional
Selector for the elements to add.
The combined set.
$('li').eq(0).addBack('.orange').length;//=> 2 Copy
$('li').eq(0).addBack('.orange').length;//=> 2
https://api.jquery.com/addBack/
Add the previous set of elements on the stack to the current set, optionally filtered by a selector.