Saber el viewport de Bootstrap 3: xs, sm, md y lg. FROM: http://stackoverflow.com/questions/14441456/how-to-detect-which-device-view-youre-on-using-twitter-bootstrap-api#answer-15150381
function findBootstrapEnvironment() {
var envs = ['xs', 'sm', 'md', 'lg'],
$el = $('<div>'),
i = 0,
env;
$el.appendTo($('body'));
for (i = envs.length - 1; i >= 0; i--) {
env = envs[i];
$el.addClass('hidden-' + env);
if ($el.is(':hidden')) {
$el.remove();
return env;
}
}
}