No need setFoo.

TODO: collapasable, copyable, download, etc

In React, if I let [foo, setFoo] = useState(null) and then in useEffect(..., [foo, setFoo]) does it make sense to pass in setFoo? Or is that not needed?In React, when you use useState() to create state in a functional component, it gives you a state variable (in your example, foo) and a function to update that state variable (setFoo). The update function (setFoo) does not change between re-renders. This means that it is stable and does not need to be included in the dependency array of useEffect or other React hooks like useMemo or useCallback.

The dependency array in a useEffect hook is intended to list all values from the component scope (such as props and state variables) that change over time and on which the effect depends. Since setFoo does not change, including it in the dependency array is unnecessary.

So, if your effect is solely using setFoo to update the state and does not directly depend on the value of foo, you do not need to include setFoo in the dependency array. You would typically only include foo if the effect needs to run when foo changes.

Here's a simplified version:

let [foo, setFoo] = useState(null);

useEffect(() => {
  // Code that only depends on `foo` and uses `setFoo` to update it
}, [foo]); // `setFoo` is not required here because it does not change

Including setFoo in the dependency array does not cause any harm, but it does not follow the intended use of the dependency array and can lead to confusion about the dependencies of your effect. It's best practice to include only the values that the effect actually depends on to make your code clearer and to avoid unnecessary executions of the effect.

No need setFoo. created at Tue Jan 20 1970 18:57:30 GMT+0000 (Coordinated Universal Time)