fadeIn() function - what change if a div is hide or not?

I see on internet that many times the function fadeIn() is preceded by the function hide(), but in fact I can't understand what's the difference between put it before or not : the 开发者_如何转开发result is the same!

Who know? :)

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The hide() is there incase it's already on show I guess, and to make sure it's hidden before they fade it in.