Testing a Socket.IO Service

What is Socket.io and How to Connect and Test With Postman

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What is Socket.IO?

Socket.IO is a library that enables low-latency, bidirectional and event-based communication between a client and a server. — https://socket.io/docs/v4/

There are several transports available, including WebSockets and long polling.

If you have ever had the following thoughts, this guide should clear it up.

• I am trying to test this WebSocket, and nothing is working…
• What the hell is this payload with a 42["subscribe", {...}] in it?
• Why can’t this library talk to this service, but this other one works?

Long polling has its share of issues; WebSockets can be tricky. It’s gotten a lot easier over the years. When I first worked with Socket.IO, it was not uncommon for a network layer to block a socket, and you would have to default to long polling for those scenarios. It’s the reason I chose Socket.IO, among a few others:

• The ability to handle the various levels of networking support with multiple transports as a fallback
• Handling disconnect/reconnect issues on the client or server