React's setState method with prevState argument

Question

I\'m new to React, just have a question on setState method. Let\'s say we have a component:

class MyApp extends React.Component {

  state = {
    count: 3
          


        

Answer 1

Both signatures can be used, the only difference is that if you need to change your state based on the previous state you should use this.setState(function) which will provide you a snapshot(prevState) from the previous state. But if the change does not rely on any other previous value, then a shorter version is recommended this.setState({prop: newValue})

this.setState(prevState =>{
   return{
        ...prevState,
        counter : prevState.counter +1
   }
})

this.setState({counter : 2})