prevstate in usestate
const [prevState, setState] = React.useState([]);
setState(prevState => [...prevState, 'somedata'] );prevstate in usestate
const [prevState, setState] = React.useState([]);
setState(prevState => [...prevState, 'somedata'] );prevstate in react
handleClick() {
this.setState(prevState => {
return {
count: prevState.count + 1
}
})
}this.setstate prevstate
this.setState(prevState => ({ n: !prevState.n }))react setState
incrementCount() {
// Note: this will *not* work as intended.
this.setState({count: this.state.count + 1});
}
handleSomething() {
// Let's say `this.state.count` starts at 0.
this.incrementCount();
this.incrementCount();
this.incrementCount();
// When React re-renders the component, `this.state.count` will be 1, but you expected 3.
// This is because `incrementCount()` function above reads from `this.state.count`,
// but React doesn't update `this.state.count` until the component is re-rendered.
// So `incrementCount()` ends up reading `this.state.count` as 0 every time, and sets it to 1.
// The fix is described below!
}Copyright © 2021 Codeinu
Forgot your account's password or having trouble logging into your Account? Don't worry, we'll help you to get back your account. Enter your email address and we'll send you a recovery link to reset your password. If you are experiencing problems resetting your password contact us
