jquery animation scrollTop dont work in ie or firefox -

a simple scroll top effect...the code doesn't work in ie or firefox works fine in chrome.

html this :

<a href="#"  class="scrolltop"><i class="glyphicon glyphicon-chevron-up"></i></a> 

and script this :

$(document.body).animate({    'scrolltop':'0' },2000); 

i have tried replace$(document.body) $("body"),nothing happen...

i posted similar answer on post:

jquery add ids paras make them linkable.

i tested following code on firefox , ie 10 , works fine.

$('html, body').animate({     scrolltop : 0 }, 500);