react-hooks

问题 What's the difference between 1 const [state, setState] = useState(0) setState(state+1) 2 const [state, setState] = useState(0) setState(...prevState => prevState+1) 回答1: In the first option, based on the documentation: The setState function is used to update the state. It accepts a new state value and enqueues a re-render of the component. In the second option, called functional update: If the new state is computed using the previous state, you can pass a function to setState . The function

问题 What's the difference between 1 const [state, setState] = useState(0) setState(state+1) 2 const [state, setState] = useState(0) setState(...prevState => prevState+1) 回答1: In the first option, based on the documentation: The setState function is used to update the state. It accepts a new state value and enqueues a re-render of the component. In the second option, called functional update: If the new state is computed using the previous state, you can pass a function to setState . The function

问题 I have a problem overriding the styles in my theme in Material UI in React. I wanted to customize the border of columnsContainer but it isn't working. only the root is working well. Check Here for Codesanbox MuiDataGrid.js export default { root: { backgroundColor: "white", border: `1px solid green`, "& .columnsContainer": { borderBottom: `1px solid 'blue' !important` } } }; 回答1: Below is the correct syntax. The changes compared to your code sandbox are: Replace .columnsContainer with

问题 I'm using a custom hook to get pull some data in from an API for use across a set of React function components. However, esLint throws up a lovely warning: React Hook useEffect has a missing dependency: 'fetchFromAPI'. Either include it or remove the dependency array. I didn't think it's a dependency, as it's inside useFetch() itself. I need to do it as I'm using await . What am I doing wrong? Is it ok to just turn off the warning for this line? Or is there a more canonical syntax I should be

问题 Say I have a parent component with two child components: const Parent = () => { const [myVar, setmyVar] = useState(false) return ( <> <MyChildComponent1 myVar={myVar} setMyVar={setMyVar} \> <MyChildComponent2 myVar={myVar} \> </> ) } Now how would I go about setting the type correctly in MyChildComponent2 ? This is what I've come up with so far: const MyChildComponent1 = ( {myVar, setMyVar}: {myVar: boolean, setMyVar: (value: boolean) => void}) = (...) Is the type for setMyvar correct? Or

问题 When using the npm package " use-dark-mode " I try to apply the hook const darkMode = useDarkMode (false); inside a function but i get an error Error: Invalid hook call. Hooks can only be called inside of the body of a function component. This could happen for one of the following reasons: before giving you the code, I want to explain in more detail, I think you already understood from the package name, I want to use dark mode in my project, I have a lot of components, I pass the dark mode

问题 When using the npm package " use-dark-mode " I try to apply the hook const darkMode = useDarkMode (false); inside a function but i get an error Error: Invalid hook call. Hooks can only be called inside of the body of a function component. This could happen for one of the following reasons: before giving you the code, I want to explain in more detail, I think you already understood from the package name, I want to use dark mode in my project, I have a lot of components, I pass the dark mode

问题 Context : New messages are added (e.g. every two seconds, using setInterval). Messages have status, either old or new. Newly added messages have a 'new' flag. After every 5 seconds, all 'new' messages are designated 'old'. (setTimeout) Problem : Timeout is not triggering until the end. New messages are added, but they remain 'new' until all messages are added. I suspect that after every update the timeout is being reset/cleared and because the updates are occurring faster than the timeout,

问题 I thought that useState needed to have a new value for it to accept updates: I have created thiscodesandbox to illustrate what I mean. I have a nested data structure like this const state = { name: "parent", data: { isExpanded: false, children: [ { name: "one", data: { isExpanded: false } }, { name: "two", data: { isExpanded: false } }, { name: "three", data: { isExpanded: false } } ] } }; I then use useState to cause rerenders when the state changes: function App() { const [tree, setTree] =

问题 I have a situation where I want to pass a value using Context + Hooks to another component, but the problem is that I do not need to import the component inside the provider to get the value in more understandable language, then imagine that I have two SideBarBlurChange components and SideBar inside the SideBarBlurChange component, I have a value in my case, this is a simple number that I want to pass inside the SideBar component, but the problem is that I don't want to import the SideBar