Add CSS code or classes to html elements with jQuery

add-css-to-html-jquery.js

// @david: add or remove classes at certain scrolling distances
// the class names in this gist are meant as an example :-)
$(window).scroll(function() {
  var y_scroll_pos = window.pageYOffset;
  var scroll_pos_test = 300;
  // set to whatever you want it to be
  
  if (y_scroll_pos > scroll_pos_test) {
    $(".menu").addClass("animated fadeInLeft");
    // or add or remove pure CSS code:
        $(".your-class").css({
      "opacity": "0"
    });
    $('.other-class').css({
      "transition": "all .5s ease-in-out 0s",
      "opacity": "0"
    });
    // end of additional css code
  } 
  else 
  {
    $(".menu").removeClass("animated fadeInLeft");
  }
});