jQuery Function that checks if an element is currently in the browser viewport.

jquery.el-in-view.js

function isScrolledIntoView(elem) {
  var $win = $(window),
      $elem = $(elem),
      docViewTop = $win.scrollTop(),
      docViewBottom = docViewTop + $win.height(),
      elemTop = $elem.offset().top,
      elemBottom = elemTop + $elem.height();

  return ((elemBottom >= docViewTop) && (elemTop <= docViewBottom) && (elemBottom <= docViewBottom) &&  (elemTop >= docViewTop));
}