Why to scroll webpage to top, i need to scroll the $("html")

i am referencing the code from snipplr

$('html, body').animate({scrollTop:0}, 'slow');

i found out actually i need to use $('html'), $('body') does not work, $('html, body') seems redundant开发者_开发技巧?

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According to this blog post (update 4) it's because html works for IE in standards mode and body works in quirks mode.