title: Product quantity increment based on product metafield
body: <p>I have succeeded in getting the quantity selector on the product page to increment based on the product meta field.</p>
  
  <p>This code is from my theme.js.liquid file:</p>
  
  <pre><code>  // Add or subtract from the current quantity
  if ($el.hasClass('ajaxcart__qty--plus')) {
    qty += productMetaQtyIncr;
  } else {
    qty -= productMetaQtyIncr;
    if (qty &lt;= 0) qty = 0;
  }
  </code></pre>
  
  <p>I placed this code in my theme.liquid head:</p>
  
  <pre><code>&lt;script&gt;const productMetaQtyIncr = {{ product.metafields.qty_incr.qty-incr }}&lt;/script&gt;
  </code></pre>
  
  <p>So this works well on the product page which is fine.
  However, when I go to my full page cart it goes back to incrementing by 1.
  This is because it is no longer pulling the product meta field as I'm not on the product page.</p>
  
  <p>If I open my AJAX sidebar cart it will update all products quantity increment based on the product page I am on, which isn't what I want.</p>
  
  <p>So, my question is how can I get the quantity selector to recognise which product it is updating?</p>
  
  <p>E.g. I have two products in my cart. Product A increments by 5 and Product B increments by 3.
  When I got to the cart (sidebar cart or the full-page cart) it knows what the product increments by without being on the product page or even if I'm on a product page and I change a different product quantity using the sidebar cart on a product page.</p>