function that returns a string of productIds separated by commas from dataLayer on orderPlaced page.

productIdsCsv.js

//function that returns a string of productIds separated by commas
for (var idx in dataLayer) {
    if (dataLayer[idx].hasOwnProperty('ecommerce')){
		return dataLayer[idx].ecommerce.purchase.products.map(function(product){ return product.id }).join(','));
    }
}