Consider the following node.js cluster config. How does one turn off the callback to prevent further on message callbacks? There happens to be no off method. I have to update the callback with a new one and it appears that all the old callbacks are being triggered as well.
cluster.on('fork', worker => {
worker.on('message', msg => {// Do something...})
})
The opposite of .on() is .removeListener() because .on() is simply an alias for .addListener(). Why they added .on() as an alias, but did not add .off() as an alias too, I don't really know (seems logical to me).
But, to be able to remove a single listener with removeListener(), you need a function reference for the function you originally attached. So, you need to save that:
cluster.on('fork', worker => {
function msgHandler(msg) {
// process message
}
// add event handler
worker.on('message', msgHandler);
// then, sometime later, to remove the event handler
worker.removeListener('message', msgHandler);
});
If you just want to remove all event listeners for a given event, you don't have to save the former function reference:
cluster.on('fork', worker => {
worker.on('message', msg => {// Do something...})
// some time later, remove all listeners for a particular message
worker.removeAllListeners('message');
});
Related answer: What is the difference between addListener(event, listener) and on(event, listener) method in node.js?
You can use removeListener method. https://nodejs.org/api/events.html#events_emitter_removelistener_eventname_listener
