A web application execution method, for a client to execute a web application on a remote server is provided. A connection status between the client and the remote server is monitored. If the connection is established, an online learning process is performed to monitor the handshakes between the client and the server, thereby constructing a virtual server. If the connection is disconnected, an offline service is activated, allowing the client to execute the web application through the virtual server. If the connection is reestablished after being disconnected, a synchronization process is performed to synchronize state machines within the virtual server and the server.