vanilla javascript update to calculate price discount for ecommerce.

ecommerceDiscount.js

const handlePricePourcentage = () => {
  const isEmpty = value =>
    value === undefined ||
    value === null ||
    (typeof value === "object" && Object.keys(value).length === 0) ||
    (typeof value === "string" && value.trim().length === 0)

  // GET REAL PRICE
  const getRealPrice = () => {
    const parent = document.getElementsByTagName("del")
    return Object.values(parent).map(tag => {
      const items = tag.getElementsByTagName("bdi")
      return Object.values(items).map(tag => Number(tag.innerHTML.split(" ")[0].split(',').join('').split('.').join('')))[0]
    })
  }
  // GET DISCOUNTEDPRICE
  const getDiscountedPrice = () => {
    const parent = document.getElementsByTagName("ins")
    return Object.values(parent).map(tag => {
      const items = tag.getElementsByTagName("bdi")
      return Object.values(items).map(tag =>  Number(tag.innerHTML.split(" ")[0].split(',').join('').split('.').join('')))[0]
    })
  }
  // GET DISCOUNT
  const getDiscount = () => {
    const realPrices = getRealPrice()
    const discountedPrices = getDiscountedPrice()
    return discountedPrices.map((price,i) => ({
      fullPrice: realPrices[i],
      discountedPrice: price,
      discount: parseFloat(100 - (100 * price / realPrices[i])).toFixed(0)
    }))
  }

  // INJECT DISCOUNT
  const injectHtml = () => {
    const discounts = getDiscount()
    const wrappers = document.getElementsByTagName("ins")
    return Object.values(wrappers).map((wrapper, i) => {
      let span = document.createElement('span')
      span.innerHTML = `${discounts[i].discount}%`
      span.classList.add("discount-percentage");
      return wrapper.appendChild(span)
    })
  }
  injectHtml()
}

handlePricePourcentage()