React state and props Note

In the state like, directly with the value of the parameter of the props,
such as

state={
  longitude:this.props.formData.longitude,
  latitude:this.props.formData.latitude
}

But being given that formData not defined, clearly he has introduced to, and later found out the reason, because I also used two

class A extends React.Component{
    constructor(){
          xxxxxxxx

    }
    state={
       longitude:this.props.formData.longitude,
       latitude:this.props.formData.latitude
    }
}

I thought it was not written in the constructor of the state, but it still went into error
after careful examination revealed

constructor(props){
          super(props)

    }

If a constructor, then the two will write, receives props, and super, otherwise props are not receiving

Reproduced in: https: //www.jianshu.com/p/f0bbbe01107c