.closest()

For each element in the set, get the first element that matches the selector by testing the element itself and traversing up through its ancestors in the DOM tree.

jQuery.support

A collection of properties that represent the presence of different browser features or bugs. Intended for jQuery's internal use; specific properties may be removed when they are no longer needed internally to improve page startup performance. For your own project's feature-detection needs, we strongly recommend the use of an external library such as Modernizr instead of dependency on properties in jQuery.support.