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Recieve & Send

Attaching to message listener

To receive game state updates, the client code must call

window.addEventListener('message', onMessage, false);

const onMessage = (evt) => {
  let gamestate =;
  let origin = evt.origin;
  let source = evt.source;
  if (!gamestate)

Jump to the Client relevant game state to see what the object holds.

Sending an action

To send an action, you must call the window.parent.postMessage method.

let action = {
  type: "move",
  payload: 3
window.parent.postMessage(action, '*');

Client's can also send actions in the following format using the acosg.js send function:

send("pick", 3);

The first parameter is always a string, second parameter can be any primitive, array, or object type.

Client relevant game state

The gamestate object received from message listener will have all these objects from Game State

  "local": {},
  "state": {},
  "players": {},
  "teams": {},
  "next": {},
  "events": {},
  "timer": {},
  "room": {}

local (object)

This game state object is client-side only. The platform will automatically add the local player object which is identical to the players game state for the local player.

"local": {
    "name": "joe",
    "rank": 1,
    "score": 100,
    "id": "8CCkf",
    "ready": true,
    "type": "X"

next (object)

 "next": { "id": "manC6" },

The next object shows which player id is allowed to make the next action. You should avoid sending if the local player is not in the id field.

When the id is '*', all players are allowed to submit an action.

timer (object)

"timer": {
    "end": 1641441249109,
    "seconds": 10,
    "sequence": 5
Timers are very important to keep games fast-paced.

In order to ensure that players with high latency (400+ms) can play, all clients automatically have the timer.end adjusted based on their latency to match server time.

For timeleft display on UI, you can use the seconds value which you can calculate the original time with:

let startTime = gamestate.timer.end - gamestate.timer.seconds * 1000;