tidio close chat button (with memory)

/* tidio close button with x days memory (no jQuery needed) */
(function() {
    tidio_close_data = {
        key: 'tidio-close-stamp'
    ,   ele_parent: '#button.chat-closed #button-body'
    ,   ele_id: 'close_button'
    };
    tidio_close_data.ele_select = tidio_close_data.ele_parent + ' #' + tidio_close_data.ele_id;

    // close, and set timestamp
    var close_tidio_chat = function(e) {
        e.stopPropagation();

        window.tidioChatApi.close();
        window.tidioChatApi.hide();

        if (localStorage) {
            localStorage.setItem(tidio_close_data.key, Date.now());
        }
    }

    // inject close button as a span positioned above and right of floating chat button
    function addCloseButton() {

        var $doc = document.getElementById("tidio-chat-iframe").contentDocument;
        var $parent = $doc.querySelector(tidio_close_data.ele_parent);

        $parent.insertAdjacentHTML('beforeend', '<span id="' + tidio_close_data.ele_id + '">X</span>');

        // now get this element we just inserted
        tidio_close_data.ele = $doc.querySelector(tidio_close_data.ele_select);
        tidio_close_data.ele.addEventListener("click", close_tidio_chat, true);

        // styling for button offset, style as you want
        var $css = `{
            font-size: 16px;
            font-weight: bold;
            position: absolute;
            width: 22px;
            background-color: #D66166;
            color: white;
            border-radius: 12px;
            top: -20px;
            right: -20px;
        }`;

        var $tidio = '<style type="text/css">' + tidio_close_data.ele_select + ' ' + $css + '</style>';
        $doc.head.insertAdjacentHTML('beforeend', $tidio);
    }

    function checkAndHide() {
        if (localStorage) {
            $stamp = localStorage.getItem(tidio_close_data.key);

            if ($stamp) {
                // if stamp exists and diff < duration, we hide the button.
                $duration_days = 7;
                $duration = $duration_days * (60 * 60 * 24 * 1000);

                if (Date.now() - $stamp < $duration) {
                    tidio_close_data.ele.click();
                }
            }
        }
    }

    function onTidioChatApiReady() {
        addCloseButton();
        checkAndHide();
    }

    if (window.tidioChatApi) {
        window.tidioChatApi.on('ready', onTidioChatApiReady);
    } else {
        document.addEventListener('tidioChat-ready', onTidioChatApiReady);
    }
})();