JS: find current bootstrap 3 breakpoint

findBootstrapEnvironment.bootstrap.js

window.findBootstrapEnvironment = function() {
    var envs = ['xs', 'sm', 'md', 'lg'];

    var $el = jQuery('<div>');
    $el.appendTo(jQuery('body'));

    for (var i = envs.length - 1; i >= 0; i--) {
        var env = envs[i];

        $el.addClass('hidden-'+env);
        if ($el.is(':hidden')) {
            $el.remove();
            return env;
        }
    }
}