Calculates price based off of qty

magentoprice.js

    var originalPrice = $('.regular-price .price').text();
    var priceStripped = originalPrice.replace('$', '');
    var priceConverted = parseFloat(priceStripped);
    var quantity = 1;

    //product page qty
    $('.sp-input').on('change', function () {
      quantity = $(this).val();
      var manuStripped = originalPrice.replace('$', '');
      var manuConverted = parseFloat(manuStripped);
      var manuOriginal = parseFloat(manuStripped);
      var priceNew = (manuConverted * quantity).toFixed(2);
      if (isNaN(quantity) === true) {
        $('.sp-input').val(1);
        //$('.regular-price .price').text("$" + manuOriginal);
      } else {
        $('.regular-price .price').text("$" + priceNew);
      }
    });

    $('.super-attribute-select').on('change', function () {
      var priceTotal = $('.regular-price .price').text();
      var priceStripped = priceTotal.replace('$', '');
      var priceConverted = parseFloat(priceStripped);

      var optprice = $('option:selected', this).attr('price');
      var priceNew = ((priceConverted + optprice) * quantity).toFixed(2);
      $('.regular-price .price').text("$" + priceNew);
    });
    $('.sp-plus').on('click', function () {
      quantity++;
      var priceNew = (priceConverted * quantity).toFixed(2);

      if (isNaN(quantity) === true) {
        $('.sp-input').val(1);
      } else {
        $('.sp-input').val(quantity);
      }
      $('.regular-price .price').text("$" + priceNew);
    });

    $('.sp-minus').on('click', function () {
      if (quantity <= 1) {
        return false;
      } else if (isNaN(quantity) === true) {
        $('.sp-input').val(1);
      } else {
        quantity--;
        $('.sp-input').val(quantity);
      }
      var priceNew = (priceConverted * quantity).toFixed(2);
      $('.regular-price .price').text("$" + priceNew);
    });