Design problem

[gevorgter]

There is a bit of "design" problem that makes this not usable.

1. You can not remove arrow function which is understandable but takes you to the actual problem if you want to be able to call .off method.
2. The handler function is not passed event_type as parameter. So I can not have the same handler for multiple events.

Real life example: I have several fields i need to get events from. Do not want to use .all in this case.

for (let i = 0; i < fields.length; i++)
emitter.on('updated_' + fields[i], ReCalculate);

function ReCalculate(val) {
..do not know which field was undated. Only have it's new value
}

---

The issue could have been easily solved with arrow function but then i can never remove it.
Also just have .on method return fn it got as a parameter. That way i can unsubscribe arrow functions as well.

[developit]

Why can't you give your arrow function a name?

for (let i = 0; i < fields.length; i++) {
  const field = fields[i];
  const fn = (val) => {
    console.log(field, val);
    emitter.off('updated_' + field, fn);
  };
  emitter.on('updated_' + field, fn);
}

[gevorgter]

I see what you saying, I do need to remove them at some point. So instead of relying on .on returning fn. I can take them from your loop.

thanks.
It would have been prettier if .on returned 'fn' that was passed to it.

[developit]

Just to close this out: wildcard event listeners do receive the type as their first argument:

emitter.on('*', (type, val) => {
  console.log(type, val);  // ["updated_foo", "bar"]
});

emitter.emit('updated_foo', 'bar');