Question about jquery slideDown

I have a div with hight 300px I want to use slideD开发者_StackOverflow社区own or any of jquery methods to slide down a part of the div not all the 300px may be just 50px

Try this DEMO

$('#clickme').click(function() {
  $('#book').animate({
      top: '+=50',
      height: '-=50'
  }, 1000, function() {
      // callback on complete.
  });
});

$("#your_div").scrollTop(50)

isn't it right?