Because you are creating the map objects inside of your component function they will be recreated on every render. Because of that your effect will set a new map as the new state which will in turn trigger another re-render and your effect being called again which leads to an infinite update loop. You can … Read more
State update is asynchronous in React. So it is possible that there would be old value in count when you’re updating it next time. Compare, for example, result of these two code samples: function Counter({initialCount}) { const [count, setCount] = useState(initialCount); return ( <> Count: {count} <button onClick={() => setCount(initialCount)}>Reset</button> <button onClick={() => { setCount(prevCount … Read more
React.memo and React.useMemo are not equivalent at all (don’t rely on naming similarity). Here’s a quote from React.memo doc: React.memo is a higher order component. So it’s a HOC that can optimize rendition of your component given that it renders the same output with the same properties. React.useMemo on the other hand is more generic … Read more
You could give an empty array as second argument to useEffect so that the function is only run once after the initial render. Because of how closures work, this will make the counter variable always reference the initial value. You could then use the function version of setCounter instead to always get the correct value. … Read more
The reference states the actual cause, By following this rule, you ensure that Hooks are called in the same order each time a component renders. That’s what allows React to correctly preserve the state of Hooks between multiple useState and useEffect calls. and provides the example that shows why this is important. Loops, conditions and … Read more
value is stale in the event handler because it gets its value from the closure where it was defined. Unless we re-subscribe a new event handler every time value changes, it will not get the new value. Solution 1: Make the second argument to the publish effect [value]. This makes the event handler get the … Read more
As G.aziz said, React.memo functions similarly to pure component. However, you can also adjust its behavior by passing it a function which defines what counts as equal. Basically, this function is shouldComponentUpdate, except you return true if you want it to not render. const areEqual = (prevProps, nextProps) => true; const MyComponent = React.memo(props => … Read more
This error throws in useNavigate. useInRouterContext will check if the component(which uses useNavigate hook) is a descendant of a <Router>. If the component is not a descendant of the <Router> component, it will throw this error. Here’s the source code to explain why you can’t use useNavigate, useLocation outside of the Router component: useNavigate uses … Read more
In my case, I renamed the file as .ts instead of .tsx. Renaming it again fixed it.
Because it’s the async promise call, so you must use a mutable reference variable (with useRef) to check already unmounted component for the next treatment of async response (avoiding memory leaks) : Warning: Can’t perform a React state update on an unmounted component. Two React Hooks that you should use in this case : useRef … Read more