我如何知道使用原始WebSocket时是否已成功发送消息？

Question

与websocket / ws接受可选的ack回调不同，原始WebSocket.prototype.send仅接受一条消息。

Answer 1

Note that sent != received ... I'm assuming you want to make sure a message was received .

Implement ACK . It's super easy and it's the only way I know to make sure the message was received.

A good enough approach would attach a message ID on the client side and send that ID as part of the message (ie as msgID in a JSON). I use a timer ID because I cancel the timer when the ACK arrives and it's a good way to keep the timer data.

When the server recognizes a msgID , it should automatically send an ACK with the same message ID before processing the rest of the message (ie, a JSON for {"event":"ACK", "data":m["msgID"]} ).

If you're using binary data, you can simply append a fixed size ID at the beginning of each message (say, 8 bytes), or append a length indicator for a dynamic sized ID.

EDIT In reflection about Remy's comment:

Yes, using timeout IDs might be relying heavily on the way that the ID "pool" is implemented.

A safer design might prefer to avoid assumption by using a counter or some other approach.

However, it should also be noted that on all the browsers with which I tested this approach, timeout IDs are always unique.

On the Mozilla Developer Documentation Site , it states that:

It is guaranteed that a timeout ID will never be reused by a subsequent call to setTimeout() or setInterval() on the same object (a window or a worker). However, different objects use separate pools of IDs.

I think this assumption is correct across the board for all browsers (subject to the ID type overflowing and resetting itself to zero).