Why isn't my "Add to Cart" snippet for Canopy theme/Shopify 2.0 working for my class button?

I'm struggling here. I'm using Canopy Theme and when we updated to Shopify 2.0, it knocked out our Added to Cart code. Now I can't get it to work again.

Here's my button code:

<button type="submit" name="add" class="btn product-add mini-form" data-btn-type="add-to-cart">

              <span class="button-text">Add to cart</span>

              <span class="loading-spinner" aria-label="Adding"></span>

             </button>

Here's where I customized the snippet:

<script type="text/javascript">
var _learnq = _learnq || [];
  var classname = document.getElementsByClassName("btn product-add mini-form" data-btn-type="add-to-cart");
var addToCart = function() {
_learnq.push(['track', 'Added to Cart', item]);
}; for (var i = 0; i < classname.length; i++) {
classname[i].addEventListener('click', addToCart, false);
}
</script>

Did I customize the snippet incorrectly?

Thanks!