gistfile1.js

var updateComparisons = function() {
    $('.interest-cost').each(function( index ) {
      var rate =  $(this).siblings('.rate-compare').val(),
          length = parseInt($(this).find('.loan-years').text(), 10),
          totalInterest = interest(rate, length, details.amount),
          $selector = $(this).find('.new-cost');
      $selector.text(totalInterest);
    });
  };