Highlight on scroll

gistfile1.js

$(window).scroll(function(){
  var top = $(window).scrollTop();
  
  var offset = 130;
  var trigger = top+offset;
  var elements = $('h1, h2, li');
  
  checkElements(trigger, elements);
});

function checkElements(top, el){
  // circle through elements
  for (var i=0; i<el.length; i++){
   
   // get top and bottom of element
   // color is triggered when in between
    var up = el[i].offsetTop;
    var height = el[i].clientHeight;
    var bot = up+height;

    if(el[i].className == 'active'){
      if(top < up || top > bot){
        el[i].className = '';
      }
    } else if (top > up && top < bot){
      el[i].className = 'active';
    }
  }
}

Wrote this code to highlight elements as you scroll down the page for my Portfolio.