How to hide all div's with same class name in a page?

Class names can not have spaces in them. So you have to think of it as 2 class names.

Eg: class="word1 word2"

Can be selected with the following:

var myVar = $('.word1.word2');

In your specific case, it becomes:

$('.rcbScroll.rcbWidth.rcbNoWrap').hide();