A jQuery object is an array-like wrapper around one or more DOM elements. To get a reference to the actual DOM elements (instead of the jQuery object), you have two options. The first (and fastest) method is to use array notation:

$( "#foo" )[ 0 ]; // Equivalent to document.getElementById( "foo" ) 

The second method is to use the .get() function:

$( "#foo" ).get( 0 ); // Identical to above, only slower. 

You can also call .get() without any arguments to retrieve a true array of DOM elements.