Twitter Bootstrap - how to detect when media queries starts

Question

which is the fastest and easy way to fire when bootstrap-responsive.css media queries go in action?

go in action = when you resize window to mobile width and site is

Answer 1

Excellent Tip, @falsarella!

For those who like this sort of thing to not affect their actual markup the following works:

$(function(){
...
var mqClasses = ["visible-xs", "visible-sm", "visible-md", "visible-lg"];
var mq = $("").appendTo($("body"));
$.each(mqClasses, function(idx, val) {
    mq.append("");
});
function checkMQ() {
    var visible = mq.find(":visible").get(0).className;
    return visible.slice(-2);
};

function checkResize(){
    switch(checkMQ){
      case 'xs' : ...; break;
      case 'sm' : ...; break;
     ...
    }
}
$(window).on('resize', checkResize);
checkResize(); //do it once when page loads.