windowサイズに合わせてhtmlを入れ替える
この例だと、
footer_operation_block_rightとfooter_operation_block_leftを入れ子に
$(document).ready(function(){
init();
function init(){resize();};
function resize(){
var _ww = $(window).width();
if ( _ww > 640 ) {
$('.footer_operation_block_right').after($('.footer_operation_block_left'));
}else{
$('.footer_operation_block_left').before($('.footer_operation_block_right'));
}
}
$(window).on('resize',function() {resize();});
});