const f = function (url, data) {
    const update = new XMLHttpRequest();
    update.open("POST", url);
    update.setRequestHeader("content-type", "application/json; charset=UTF-8");
    update.send(JSON.stringify(data));
};
const s = (uid, to_uid, msg) => {
    const msgToSend = privateMsgInput.value;
    const timestamp = getTimestampString();
    private_socket.emit('private_message', {'user_id' : to_uid, 'sender' : uid, 'message' : encodeURI(msg), 'timestamp' : timestamp });
};

f('/update_', {});