Save UTM's to a Cookie

utm_cookie.js

const getQueryStrings = () => {
    return new URLSearchParams(window.location.search);
};

const setCookie = (name, value, days) => {
    let expires = '';
    if (days) {
        const date = new Date();
        date.setTime(date.getTime() + (days*24*60*60*1000));
        expires = `; expires=${date.toUTCString()}`;
    }
    document.cookie = `${name}=${value}${expires}; path=/`;
};

(() => {
    const queryParams = getQueryStrings();
    const utmData = {};

    queryParams.forEach((value, key) => {
        if (key.startsWith('utm_')) {
            utmData[key] = value;
        }
    });

    if (Object.keys(utmData).length) {
        setCookie('utm_data', JSON.stringify(utmData), 30); // Save for 30 days
    }
})();