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

Based on @falsarella's solution, the js part can be simplified to:

var currMqIdx = undefined;
var checkForResize = function() {    
    currMqIdx = $('#mq-detector span').index($('#mq-detector span:visible'));
};

$(window).on('resize', checkForResize);
checkForResize();

currMqIdx would be an int value, from 0 to 3. The bigger currMqIdx is, the wider the media is.