Jquery DOM Elements as selectors
jQuery accepts a wide variety of parameters, and one of them is an actual DOM element. Passing a DOM element to jQuery will cause the underlying array-like structure of the jQuery object to hold that element.
jQuery will detect that the argument is a DOM element by inspecting its nodeType.
The most common use of a DOM element is in callbacks, where the current element is passed to the jQuery constructor in order to gain access to the jQuery API.
Such as in the each callback (note: each is an iterator function).
$(".elements").each(function(){
//the current element is bound to `this` internally by jQuery when using each
var currentElement = this;
//at this point, currentElement (or this) has access to the Native API
//construct a jQuery object with the currentElement(this)
var $currentElement = $(this);
//now $currentElement has access to the jQuery API
});