state react
class Example extends React.Component {
constructor(props) {
super(props);
this.state = {
count: 0
};
}
render() {
return (
<div>
<p>You clicked {this.state.count} times</p>
<button onClick={() => this.setState({ count: this.state.count + 1 })}>
Click me
</button>
</div>
);
}
}change state in react
import React, {Component} from 'react';
class ButtonCounter extends Component {
constructor() {
super()
// initial state has count set at 0
this.state = {
count: 0
}
}
handleClick = () => {
// when handleClick is called, newCount is set to whatever this.state.count is plus 1 PRIOR to calling this.setState
let newCount = this.state.count + 1
this.setState({
count: newCount
})
}
render() {
return (
<div>
<h1>{this.state.count}</h1>
<button onClick={this.handleClick}>Click Me</button>
</div>
)
}
}
export default ButtonCounterhow to update state in react
// Correct
this.setState(function(state, props) {
return {
counter: state.counter + props.increment
};
});updatig state in react
return {
...state,
(updates here)
}set state
setState({ searchTerm: event.target.value })changing state value react
const [a, b] = React.useState(['hi','world']);
const dup = [...a]; //won't work without spread operator
b(dup);Copyright © 2021 Codeinu
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