You can think of these as pure functions because they will always render and behave the same, given the same props. Go with functional if your component doesn't do much more than take in some props and render. Premature optimisations are the root of all evil - worry about this when it's a problem. However, bear in mind that this may make your code (microscopically) worse in performance.īut honestly, I have never heard of redefining functions being a bottleneck in React apps. If they are, you can prevent redefining functions using useCallback and useMemo hooks. Whilst true, please consider if your components are really rendering at such a speed or volume that this would be worth concern. "Event handling functions are redefined per render in functional components" An example might explain this more clearly:Īs a small aside, I have heard a number of people discussing not using functional components for the performance reasons, specifically that
State can be replicated with useState(), whose return value can be destructured to a reference of the state and a function that can set the state (i.e., const = useState(initState)). As there are none, useEffect() runs once, on first mount. New Answer: Much of the below was true, until the introduction of React Hooks.ĬomponentDidUpdate can be replicated with useEffect(fn), where fn is the function to run upon rerendering.ĬomponentDidMount methods can be replicated with useEffect(fn, ), where fn is the function to run upon rerendering, and is an array of objects for which the component will rerender, if and only if at least one has changed value since the previous render.
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