[x-yuri]

UTSL, там все есть

data: function( elem, name, data, pvt /* Internal Use Only */ ) {
		if ( !jQuery.acceptData( elem ) ) {
			return;
		}

		var internalKey = jQuery.expando, getByName = typeof name === "string", thisCache,

			// We have to handle DOM nodes and JS objects differently because IE6-7
			// can't GC object references properly across the DOM-JS boundary
			isNode = elem.nodeType,

			// Only DOM nodes need the global jQuery cache; JS object data is
			// attached directly to the object so GC can occur automatically
			cache = isNode ? jQuery.cache : elem,

			// Only defining an ID for JS objects if its cache already exists allows
			// the code to shortcut on the same path as a DOM node with no cache
			id = isNode ? elem[ jQuery.expando ] : elem[ jQuery.expando ] && jQuery.expando;

		// Avoid doing any more work than we need to when trying to get data on an
		// object that has no data at all
		if ( (!id || (pvt && id && !cache[ id ][ internalKey ])) && getByName && data === undefined ) {
			return;
		}

		if ( !id ) {
			// Only DOM nodes need a new unique ID for each element since their data
			// ends up in the global cache
			if ( isNode ) {
				elem[ jQuery.expando ] = id = ++jQuery.uuid;
			} else {
				id = jQuery.expando;
			}
		}

		if ( !cache[ id ] ) {
			cache[ id ] = {};

			// TODO: This is a hack for 1.5 ONLY. Avoids exposing jQuery
			// metadata on plain JS objects when the object is serialized using
			// JSON.stringify
			if ( !isNode ) {
				cache[ id ].toJSON = jQuery.noop;
			}
		}

		// An object can be passed to jQuery.data instead of a key/value pair; this gets
		// shallow copied over onto the existing cache
		if ( typeof name === "object" || typeof name === "function" ) {
			if ( pvt ) {
				cache[ id ][ internalKey ] = jQuery.extend(cache[ id ][ internalKey ], name);
			} else {
				cache[ id ] = jQuery.extend(cache[ id ], name);
			}
		}

		thisCache = cache[ id ];

		// Internal jQuery data is stored in a separate object inside the object's data
		// cache in order to avoid key collisions between internal data and user-defined
		// data
		if ( pvt ) {
			if ( !thisCache[ internalKey ] ) {
				thisCache[ internalKey ] = {};
			}

			thisCache = thisCache[ internalKey ];
		}

		if ( data !== undefined ) {
			thisCache[ name ] = data;
		}

		// TODO: This is a hack for 1.5 ONLY. It will be removed in 1.6. Users should
		// not attempt to inspect the internal events object using jQuery.data, as this
		// internal data object is undocumented and subject to change.
		if ( name === "events" && !thisCache[name] ) {
			return thisCache[ internalKey ] && thisCache[ internalKey ].events;
		}

		return getByName ? thisCache[ name ] : thisCache;
	},

http://code.jquery.com/jquery-1.6.js