Show HN: Socket-call – Call socket.io events like normal JavaScript functions
30 bperel 12 6/16/2025, 11:40:54 AM github.com ↗
Hello HN,
I built a Typescript library (named socket-call, for lack of a more sexy name) whose goal is to be able to call socket.io events as regular functions.
So you declare your server-side like so:
...
const listenEvents = (services: UserServices) => ({
// Add your events here, the name of the event is the name of the function
login: async (username: string) => {
services._socket.data.user = { username };
console.log(`User ${username} logged in`);
setInterval(() => {
// Calling an event that's handled client-side
services.showServerMessage(`You're still logged in ${username}!`)
}, 1000);
return `You are now logged in ${username}!`;
},
});
and then on the client side you call them like normal async Javascript functions (and you can also create client-side event handlers): ...
const user = socket.addNamespace<UserEmitEvents, UserListenEvents>(
'/user'
);
// Calling an event that's declared server-side
user.login(username.value).then((message) => {
console.log('Server acked with', message);
});
// Handling an event that is sent by the server
user.showServerMessage = (message) => {
console.log('Server sent us the message', message);
}
I use this library for my own projects and would be interested to receive feedback about it :-)
I did something similar using VSCode's core ipc / rpc which only requires a transport (protocol) to implement {send, onMessage}. I use it in a Chrome extension so I have to implement my own socket.io and port message passing protocols. Some of the benefits are being able to send a message from MAIN world of an injected content script (if you want to intercept all fetch and XMLHttpRequest requests, for example) through a tunnel in the isolated world content script to the side panel which could theoretically tunnel it to a server over socket.io. If I have a Math service, for example, that only adds two numbers, it can be called from anywhere in the system with `await mathService.add(1,1);` with mathServer being dependency injected using constructor(@IMathService private readonly mathService: IMathService). This is how VSCode manages calling code across hundreds of different isolated JavaScript runtime environments.
What I did was a bit overkill and likely trpc would have been good enough if I knew about it when I started.
[0] https://github.com/bperel/socket-call/blob/e0076d7887397a92a...
[1] https://github.com/microsoft/vscode/blob/24c0ff16c250f2b39ee...
In fact, websockets work so well I use them as a generic TCP replacement, because the message oriented transport model gives me 99% of what I need with the exception of custom message types. Leaving that out was a massive letdown to me, because you now need to carry a way to identify the message type inside the body, rather than just throwing the message itself into the appropriate protocol parser (e.g. a schema based binary format).
It doesn't look difficult at all now I look at it https://javascript.info/websocket
Eh... While I agree that socket.io is one of those libraries you could probably "write" in an afternoon, and Websockets are simple, there are a couple of things that are kinda painful to rewrite time after time:
[0] https://docs.convex.dev/quickstart/script-tag