set height of all elements

set height of all elements

on resize I want to do something like that :

  1. $(document).ready(function() {
  2. var newWidth = $('.span3').width();
  3. $('.box').height(newWidth);
  4. });

I get the width of any (or the first) .span3  in my page  and all the .box of the document must have   height:.span3-height

thanks for helping