Reshaping Data For GA4

The most common real task: the site pushes some ecommerce data, but not in the shape GA4 documents. Rather than beg a developer to rewrite the dataLayer, adapt it in a Custom JS variable.

// The site gives you this:
// dataLayer.push({ event: 'order', products: [
//   { sku: 'AUR-WH-09', title: 'Aurora Headphones', cost: '129.00', qty: 1 }
// ], order_total: '129.00' })

// Custom JS variable → GA4 'items'
function () {
  var products = {{DLV - products}} || [];
  return products.map(function (p) {
    return {
      item_id: p.sku,
      item_name: p.title,
      price: Number(p.cost),
      quantity: p.qty,
    };
  });
}

Then your GA4 purchase tag references this variable for items and a second one (Number({{DLV - order_total}})) for value. The site didn't change; you bridged the gap in GTM.