Sum Steam purchase history from https://store.steampowered.com/account/history

purchaseHistory.js

// Run in console or as a snippet in Chrome
(function() {
const parseUs = x => parseFloat(x.replace(",",""));
const parseEu = x => parseFloat(x.replace(/[,.]/g, y => y == "," ? "." : ","))
const parsers = new Map([
    [",", parseEu],
    [".", parseUs]
]);
const matcher = /^([^\d]?)([\d\,\.]+\d\d)([^\n\d]?)(\nCredit|)/m;
const matchNode = x => matcher.exec(x.innerText);
const mapMatch = (mt) => {
    const [_,c1,amount,c2, credit] = mt;
    const currency = c1 || c2;
    const parser = parsers.get(amount[amount.length -3]);
    return {currency, amount: parser(amount), credit: !!credit};
};
const reducePrices = (acc, {currency, amount, credit}) => {
    const previous = acc.get(currency) || 0;
    if(credit) amount = -amount;
    acc.set(currency, previous + amount);
    return acc;
};

return Array.from(document.querySelectorAll('td.wht_total'))
    .map(matchNode)
    .map(mapMatch)
    .reduce(reducePrices, new Map());
})();