Test max cookie value

test-max-cookie-value.js

// RFC: https://datatracker.ietf.org/doc/html/rfc6265#section-6.1
// "measured by the sum of the length of the cookie's name, value, and attributes"
(function testMaxCookieSize (cookieName = "test-cookie", fillWith = "1") {
    const setCookie = (name, value) => {
        const formattedValue = `${value}; path=/; domain=${document.location.host}`;
        document.cookie = `${name}=${formattedValue}`;
    };

    const getCookie = cookieName => {
        const name = cookieName + "=";
        const decodedCookie = decodeURIComponent(document.cookie);
        const ca = decodedCookie.split(";");
        for (let i = 0; i < ca.length; i++) {
            let c = ca[i];
            while (c.charAt(0) === " ") {
                c = c.substring(1);
            }
            if (c.indexOf(name) === 0) {
                return c.substring(name.length, c.length);
            }
        }
        return "";
    };

    let cookieSuccessfullySet = true;
    let size = 1000;

    console.log("Testing max cookie size. Starting at length:", size);

    while (cookieSuccessfullySet) {
        const cookieValue = new Array(size).fill(fillWith).join("");    
        setCookie(cookieName, cookieValue);
        const storedCookieValue = getCookie(cookieName);
        if (cookieValue === storedCookieValue) {
            size++;
        } else {
            cookieSuccessfullySet = false;
            console.log("Max cookie size:", size);
        }
    }
})("test-cookie", "😀");