Prevent an effect from firing at mount

Recently I have been encountering a lot of cases where I wanted to have an effect fire when a variable changes, but not when the component mounts, similar to how componentDidUpdate behaves. I created this handy helper hook which I’ve since used in a lot of places:

import React from "react";

// A useEffect that doesn't fire at the first render
export const useSubsequentEffect = (fn, deps) => {
  const isMountedRef = React.useRef(false);
  React.useEffect(() => {
    if (!isMountedRef.current) {
      isMountedRef.current = true;
    return fn();
  }, deps);

Use it as you would normally use an effect.