rosbridge how to subscribe from multi rostopic

edit

You can reuse callbacks for multiple subscription requests and as the handler for incoming messages.

subscription_ok_callback = function(rsp) {
    alert("subscribed to /sensorPacket");
}

connection.callService("/rosjs/subscribe", '["/a", 0]', subscription_ok_callback);
connection.callService("/rosjs/subscribe", '["/b", 0]', subscription_ok_callback);

message_received_callback = function(msg) {
    alert("received a message: " + msg);
}

connection.addHandler("/a", message_received_callback);
connection.addHandler("/b", message_received_callback);