.prev()

Get the immediately preceding sibling of each element in the set of matched elements. If a selector is provided, it retrieves the previous sibling only if it matches that selector.

.map()

Pass each element in the current matched set through a function, producing a new jQuery object containing the return values.

.is()

Check the current matched set of elements against a selector, element, or jQuery object and return true if at least one of these elements matches the given arguments.