Extension to jQuery to imitate the Form.elements array for any arbitrary descendant of a form.

jquery.subsection.js

/*
Serialize Subsection - jquery.subsection.js
Copyright (c) 2008 Nathan Hammond
Released under the MIT license.

With thanks to Michael Geary, Diego Perini, John-David Dalton, John Resig, and Garrett Smith for vetting elements of this idea.
Requires jQuery revision 5826 or later with the change to jQuery.fn.serializeArray() to query this.elements.
Requires Ancestry plugin.
*/

jQuery.fn.serializeSubsection = function ( refresh ) {
	refresh = refresh || false; // Flag to identify if we should recalculate the subelements.

	// Set up the .elements array on all matched DOM elements.
	this.map(function() {
		// Short circuit.
		if ( !refresh && this.elements ) return;

		// Traverse upward until we find the form.
		for ( var form = this; !jQuery.nodeName( form, "form" ); form = form.parentNode )
			if ( !form ) return; // Better luck next time, this element isn't in a form.

		// Identity crisis.
		var self = this;

		// Get the array for the form elements.
		// Filter it to only have the descendants of the subsection.
		// Store it as if it were the relevant HTMLCollection for the subsection element.
		this.elements = jQuery(jQuery.makeArray(form.elements)).descendantOf(self).get();

	});
	return this.serializeArray();
};