UseMutation's onSuccess handler vs. the mutationFn

[jennings]

Is there any functional difference between passing an onSuccess handler to useMutation and just doing the same logic inside the mutationFn? The values returned by useMutation seem to be identical in both cases.

useMutation({
  mutationFn: async () => {
    await fn1();
    await fn2();
  }
})

useMutation({
  mutationFn: async () => {
    await fn1();
  },
  onSuccess: async () => {
    await fn2();
  }
})

[TkDodo]

slight difference is that onSuccess runs after the global cache level callbacks, so if one of those throws, the onSuccess handler of useMutation isn’t called anymore.

[jennings]

Makes sense, thank you!