在不使用 useEffect 钩子的情况下启动计时器间隔

Question

I want to start a timer interval in react native without using useEffect hook, in y case I want to start a timer when a promise resolves and change a state variable each second, how can I do this without using useEffect hook?

i tried this:

useEffect(
  () => {
    const id = setInterval(() => {
        
     setCounter(counter+1)
    
    }, 1000);
    return () => {
      clearInterval(id);
    };
  },
  [] // empty dependency array
);

And while it works I need to start the timer calling it from a normal function and not a hook.

Answer 1

Any side effects (including starting a timer) should not belong to the main body of the component function. Instead, it is best to delegate these things to a useEffect() hook.

If I understood your question correctly, you can still start that timer inside a hook, simply call the normal function inside.

Eg it can be this simple if your normal function already returns a function to clean itself:

useEffect(() => startTimer(setCounterCallback), [])

Oh, and if the plan is to start it after a promise resolves, also wrap that async function inside the same useEffect() :

useEffect(() => {
  const promise = Promise.resolve();
  promise.then(() => startTimer(setCounterCallback));
}, []);