How to double and half a count in react?

Question

I would like to be able to double and to half a number. How should I modify handleClick() method to do it?

I tried to modify count:

 count: prevState.count + 1

so it will be count: prevState.count + prevState.count or prevState.count * 2

but it didn't work.

 import React from "react" class App extends React.Component { constructor() { super() this.state = { count: 0 } this.handleClick = this.handleClick.bind(this) } handleClick() { this.setState(prevState => { return { count: prevState.count + 1 } }) } render() { return ( <div> <h1>{this.state.count}</h1> <button onClick={this.handleClick}>Change!</button> </div> ) } } export default App

Answer 1

这将不起作用，因为您将 0 加倍。所以 0*0=0