I was going through the hooks documentation when I stumbled upon useRef. Looking at their example… function TextInputWithFocusButton() { const inputEl = useRef(null); const onButtonClick = () => { // `current` points to the mounted text input element inputEl.current.focus(); }; return ( <> <input ref={inputEl} type=”text” /> <button onClick={onButtonClick}>Focus the input</button> </> ); } …it … Read more
According to the docs: componentDidUpdate() is invoked immediately after updating occurs. This method is not called for the initial render. We can use the new useEffect() hook to simulate componentDidUpdate(), but it seems like useEffect() is being ran after every render, even the first time. How do I get it to not run on initial … Read more
I’m trying to use react hooks for a simple problem const [personState,setPersonState] = useState({ DefinedObject }); with following dependencies. “dependencies”: { “react”: “^16.8.6”, “react-dom”: “^16.8.6”, “react-scripts”: “3.0.0” } but I’m still getting the following error: ./src/App.js Line 7: React Hook “useState” is called in function “app” which is neither a React function component or a … Read more
How to push element inside useState array React hook? Is that as an old method in react state? Or something new? E.g. setState push example ? 10 Answers 10
Let’s say I have 3 inputs: rate, sendAmount, and receiveAmount. I put that 3 inputs on useEffect diffing params. The rules are: If sendAmount changed, I calculate receiveAmount = sendAmount * rate If receiveAmount changed, I calculate sendAmount = receiveAmount / rate If rate changed, I calculate receiveAmount = sendAmount * rate when sendAmount > … Read more
In the official docs of React it mentions – If you’re familiar with React class lifecycle methods, you can think of useEffect Hook as componentDidMount, componentDidUpdate, and componentWillUnmount combined. My question is – how can we use the componentWillMount() lifecyle method in a hook? 21 Answers 21
I was trying the useEffect example something like below: useEffect(async () => { try { const response = await fetch(`https://www.reddit.com/r/${subreddit}.json`); const json = await response.json(); setPosts(json.data.children.map(it => it.data)); } catch (e) { console.error(e); } }, []); and I get this warning in my console. But the cleanup is optional for async calls I think. I … Read more
The useEffect React hook will run the passed in function on every change. This can be optimized to let it call only when the desired properties change. What if I want to call an initialization function from componentDidMount and not call it again on changes? Let’s say I want to load an entity, but the … Read more
I am trying to learn hooks and the useState method has made me confused. I am assigning an initial value to a state in the form of an array. The set method in useState is not working for me, both with and without the spread syntax. I have made an API on another PC that … Read more
With React 16.8.6 (it was good on previous version 16.8.3), I get this error when I attempt to prevent an infinite loop on a fetch request: ./src/components/BusinessesList.js Line 51: React Hook useEffect has a missing dependency: ‘fetchBusinesses’. Either include it or remove the dependency array react-hooks/exhaustive-deps I’ve been unable to find a solution that stops … Read more
