Add columns for monthly cost to AWS pricing tables

aws-show-monthly-cost.js

function findHourlyPriceColumns(table) {
    for (const row of table.querySelectorAll("thead tr")) {
        const headers = Array.from(row.querySelectorAll("th"));
        const columns = headers.reduce(function(acc, current, index) {
            if (/hourly/i.test(current.innerText) || /price per hour/i.test(current.innerText)) {
                acc.push(index)
            }
            return acc;
        }, []);
        if (columns.length > 0) return {hourlyColumns: columns, totalColumns: headers.length};
    }
    return null;
}

function extractHourlyPrice(text) {
    return parseFloat(text.match(/[0-9.]+/)[0]);
}

function insertMonthlyPrices(table, hourlyColumns) {
    table.querySelectorAll("tbody tr").forEach(function(row) {
        const cells = row.querySelectorAll("td");
        if (cells.length != hourlyColumns.totalColumns) return;
        hourlyColumns.hourlyColumns.forEach(function(index) {
            const hourlyPrice = extractHourlyPrice(cells[index].innerText);
            const monthlyPrice = (hourlyPrice * 24 * 30).toFixed(0);
            const monthlyCell = document.createElement("td");
            monthlyCell.innerText = `$${monthlyPrice}/mo`;
            row.insertBefore(monthlyCell, cells[index].nextSibling);
        })
    })
}

document.querySelectorAll(".aws-table table").forEach(function(each) {
    const columns = findHourlyPriceColumns(each)
    if (!columns) return;
    insertMonthlyPrices(each, columns)
})