  child.style.color = color;
        }
        child.innerText = line;
        document.getElementById('message-list').appendChild(child);
    }

    function post(url, data) {
        return new Promise((resolve, reject) => {
            var xhr = new XMLHttpRequest()
            xhr.open("POST", url, true)
            xhr.setRequestHeader("Content-type", "application/json-patch+json");

            xhr.onreadystatechange = function () {
                if (this.readyState === 4) {
          