есть ли в Jquery SlideUp SlideDown свойство Step? как заменить, эммулировать slideUp animate?

jQuery.exists = function(selector) {
return ($(selector).length > 0);
}


var isanimated=false;


function myslideDown(selector)
{
if (isanimated) return false;

isanimated=true;



selector.animate({
"height": "show",
"marginTop": "show",
"marginBottom": "show",
"paddingTop": "show",
"paddingBottom": "show"
},
{

step: function( now, fx ) {
// $(this).height();

var data = fx.elem.id + " " + fx.prop + ": " + now;
$( "body" ).append( "" );


}

,
complete: function(){

console.log( 'DONE!!');isanimated=false;
}


});

}

function myslideUp(selector)
{
if (isanimated) return false;

isanimated=true;

selector.animate({
"height": "hide",
"marginTop": "hide",
"marginBottom": "hide",
"paddingTop": "hide",
"paddingBottom": "hide"
},
{


step: function( now, fx ) {

console.log($(this).height());
var data = fx.elem.id + " " + fx.prop + ": " + now;
$( "body" ).append( "" );

} ,
complete: function(){
isanimated=false;
}
});

}











});