What does jquery $ actually return?

Question

From Rick Strahl's description:

The jQuery Object: The Wrapped Set: Selectors return a jQuery object known as the "wrapped set," which is an array-like structure that contains all the selected DOM elements. You can iterate over the wrapped set like an array or access individual elements via the indexer ($(sel)[0] for example). More importantly, you can also apply jQuery functions against all the selected elements.

About returning nothing:

Does it always return an array? Does it return null?

You always get the same thing back, whether or not it has any contents is the question. Typically you can check this by using .val() (e.g. $('.myElem').val())

It doesn't return an array, it returns a jQuery object. The jQuery object is what contains all the special jQuery methods.

It never returns null, or another type. If one element is found, the jQuery object will have only one child. If no elements are found, the jQuery object will be empty.

The jQuery function (i.e. "$") always returns a jQuery object in every instance.

As another answerer mentioned, it always returns the jQuery object.

This object always contains an array of elements (even if it is an empty array, or an array with just one object).

If you'd like to use the returned object "directly", as in, as a plain element, you can do one of the following:

$('selector')[0] // element
$('selector').get(0) // element
$('selector').length // number of elements in the array

From the jQuery documentation:

The jQuery object itself behaves much like an array; it has a length property and the elements in the object can be accessed by their numeric indices [0] to [length-1]. Note that a jQuery object is not actually a Javascript Array object, so it does not have all the methods of a true Array object such as join().

The fact that $() always returns the jQuery function lets you chain jQuery function calls judiciously.

Jquery selector mechnism

$("..") , the jquery selector, is used to select matched elements.

Return value

It always return an array-like jquery object, which has a length property,

Call method on returned jquery object

Methods of jquery could be called on the object, and apply to those selected elements,

Access original element by index

The selected elements, are store as property of the object, their property name are index numbers start from 0,
thus could be accessed by index, start from 0,
after get the original element, you can treat it as if get by document.getElementXxx().

Wrap an original element to a jquery object

After get the original element, you can wrap it to be a jquery object, by calling $(originalEle),
then you can call jquery methods on the wrapped object.