foxtrot-price.js

// ==UserScript==
// @name         Show sale price
// @namespace    http://tampermonkey.net/
// @version      1.0
// @description  Show sale price
// @author       Ivan
// @match        https://www.foxtrot.com.ua/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';
document.querySelectorAll('.card__body').forEach(body => {
    const priceEl = body.querySelector('.card-price')
    const discountEl = body.querySelector('.card__bonus')
    const titleEl = body.querySelector('.card__title')

    const priceValue = priceEl.textContent.replace(/\D/g, '');
    const discountValue = discountEl.textContent.replace(/\D/g, '');
    const winPercent = 100-Math.round((priceValue - discountValue) / priceValue * 100);
    titleEl.textContent = `${winPercent}% - ${titleEl.textContent.replace(/\d+%/, '')}`;
    console.log(priceValue, discountValue, winPercent);
    const size = 10 + winPercent;
    priceEl.style.fontSize = size + 'px';
    discountEl.style.fontSize = size + 'px';
})

})();