let request = new XMLHttpRequest();
request.open(
  "GET",
  "https://www.unisport.dk/api/products/batch/?list=179249,179838,174351,180011,180020,178429"
);
request.onload = function() {
  let data = JSON.parse(request.responseText).products;
  console.log(data);
  renderHTML(data);
  currencyFormat(data);
};
request.send();

function renderHTML(data) {
  let slider = document.getElementById("slider");
  for (let product of data) {
    //you dont need to pass the whole data since you use only price, pass only price
    let converted_price = currencyFormat(product.price);
    slider.innerHTML +=
      '<div class="product">' +
      '<img class="item-image" src="' +
      product.image +
      '" alt="image" width="100" height="100">' +
      '<div class="product-description">' +
      //notice here
      converted_price +
      "</div>" +
      product.name +
      '<div class="size">' +
      '<select name="size"><option value="">Choose Size</option><option value="'+product.sizes+'"</option></select></div>'+
      "</div>" ;
  }
}
function currencyFormat(price) {
      let formatter = new Intl.NumberFormat("da-DK", {
        style: "currency",
        currency: "DKK",
        minimumFractionDigits: 2
      });
      let formatted = formatter.format(price);
      // console.log(formatted);
      return formatted;
    }