javascript - Check if object is a jQuery object

itemprop="text">

Is there a fast way of checking if an
object is a jQuery object or a native JavaScript
object?

example:

var
            o = {};
var e = $('#element');

function doStuff(o)
            {
 if (o.selector) {
 console.log('object is jQuery');

            }
}


doStuff(o);
doStuff(e);

obviously,
the code above works but it's not safe. You could potentially add a selector key to the
o object and get the same result. Is there a better way of
making sure that the object actually is a jQuery
object?

Something in line with
(typeof obj == 'jquery')

Answer

You can use the href="https://developer.mozilla.org/en/JavaScript/Reference/Operators/Special_Operators/Instanceof_Operator"
rel="noreferrer">instanceof
operator:

obj
            instanceof
            jQuery

Explanation:
the jQuery function (aka $) is
implemented as a href="https://developer.mozilla.org/en/Core_JavaScript_1.5_Guide/Working_with_Objects#Using_a_constructor_function"
rel="noreferrer">constructor function. Constructor functions are to be
called with the new
prefix.

When you call
$(foo), internally jQuery translates this to new
jQuery(foo)¹. JavaScript proceeds to initialize
this inside the constructor function to point to a new instance
of jQuery, setting it's properties to those found on
jQuery.prototype (aka jQuery.fn).
Thus, you get a new object where instanceof
jQuery is
true.

/>

¹_{It's actually
new jQuery.prototype.init(foo): the constructor logic has been
offloaded to another constructor function called init, but the
concept is the same.}