how to ensure data consistency when using Depth subscription ?

[illusionoff]

Depth subscription version 3 : https://www.gate.io/docs/websocket/index.html?javascript#depth-subscription
When subscribing, 'depth.subscribe', ["ETH_USDT", 5, "0.0001"]
The first message comes with a value:
{ "method": "depth.update", "params": [ **_true_**, { asks: [Array], bids: [Array], **_id: 1736394129_** },
Аnd contains the complete specified,in this case "5" ORDERBOOK and id.
But subsequent messages with a value of false do not contain an id.
How can you know for sure that a message has not been lost without comparing the id?

[revilwang]

We suggest using the new WebSocket v4 instead.

[illusionoff]

Unfortunately there is no documentation for javascript v.4 . Im Junior

And yet, maybe you can advise how this functionality was provided in v3?

[revilwang]

The bad news is that there is no certain way to check order book consistency in v3. We are planing to support v4 websocket with JavaScript.