(function() {
    function addWhatsApp() {
        var innerHtml = document.createElement("a");
            innerHtml.href = ''; //сюда нужно вставить ссылку на whatsapp
            innerHtml.target = "_blank";
            innerHtml.setAttribute('class', 'carrotquest-social-messenger-button carrotquest-social-messenger-button-whatsapp');
        var innerDiv = document.createElement('div');
            innerDiv.textContent = 'Написать нам в WhatsApp';
            innerDiv.setAttribute('class', 'carrotquest-social-messenger-button-title');
        innerHtml.appendChild(innerDiv);
        document.querySelector('#carrotquest-social-messenger-buttons').appendChild(innerHtml);
    };

    var css = '.carrotquest-social-messenger-button.carrotquest-social-messenger-button-whatsapp{background-color: #25D366!important; background-image: url(https://files.carrotquest.io/message-images/100/100-1574239739864-kyjphllb.png)!important; background-size: 60px auto !important;}',
        head = document.head || document.getElementsByTagName('head')[0],
        style = document.createElement('style');
    style.type = 'text/css';
    if (style.styleSheet){
        style.styleSheet.cssText = css;
    } else {
        style.appendChild(document.createTextNode(css));
    };
    head.appendChild(style);

    var checkSocButtons = setInterval(function() {
        if (document.querySelector('#carrotquest-social-messenger-buttons')!=null) {
            clearInterval(checkSocButtons);
            addWhatsApp();
        };
    }, 500);

    carrotquest.addCallback('messenger_closed', function() {
        var checkSocButtons = setInterval(function() {
            if (document.querySelector('#carrotquest-social-messenger-buttons')!=null) {
                clearInterval(checkSocButtons);
                addWhatsApp();
            };
        }, 100);
    });
}());