modernizr.load-js-conditionally.js

$(document).ready(function() {

  /*####
  Load in script only when a DOM element exists.
  Use callback function to run 
  ####*/

  Modernizr.addTest('foo', $('.bar').length > 0);

  Modernizr.load({
    test: Modernizr.foo,
    yep: 'https://ajax.googleapis.com/ajax/libs/jqueryui/1.8.16/jquery-ui.js',
    callback: function () {
      //Run this when the 'foo' condition is met
      $('.bar').console.log('I detected the "bar" class, loading in jQuery UI');
    }
  });

});