SSE EventSource also has built-in auto-reconnect, and it doesn’t even need to support failover to long polling.

Neither of those being built into a third party websocket library are actually advantages for websocket… they just speak to the additional complexity of websocket. Plus, long polling as a fallback mechanism can only be possible with server side support for both long polling and websocket. Might as well just use SSE at that point.

2 lines vs 5 lines. did you check your payload size after adding socket.io? you added way more than 2 lines.

long polling shouldn’t be needed anymore, and auto reconnect is trivial to implement.