How to use useEffect callback with event callbacks
I was running some code like this:
useEffect(() => {
if (!socket) return
socket.on('newuserconnected', (username) => {
console.log(connectedusers)
})
}, [socket])to initialize a callback for an event newuserconnected on a socket.io connection.
I assumed that after doing so, any time I called that event on the server, the client-side (React app) would print the current value at runtime of the variable connectedusers (imagine I was updating it somewhere else in the app).
But no, the value of that variable was “stuck in time” at the moment I defined that event.
What I had to do to fix the problem was to add that variable value to the list of variables that the useEffect call depends on:
useEffect(() => {
//...
}, [socket, connectedusers])download all my books for free
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