How to toggle a Boolean in react native?

Question

I am struggling to toggle a Boolean state from true to false when the result is undefined . I have tried a lot but didn't work.

The boolean state in constructor is defined as follows :

class UserInfo extends Component{
constructor(props){
    super(props);
    this.state = {
    token : '',
    isVisible : true,
   };
}

This function should check if token holds a value or undefined and then continue to execute the right condition accordingly. However, when token is undefined the isVisible is not getting toggled to false and it will remain true no matter what.

Any suggestions I would be much appreciated.

 ToggleFunction = (token) => {
    if (this.state.token === undefined){
      this.setState({
        isVisible: !this.state.isVisible,
        });   
  }
  else {
    this.setState(state => ({

      isVisible: state.isVisible


    }));
  }
};

Answer 1

In your ToggleFunction, you're checking this.state.token === undefined as opposed to token === undefined from the parameter of the method call.

Try:

ToggleFunction = (token) => {
    if (token === undefined){
      this.setState({
        isVisible: !this.state.isVisible,
        });   
  }
  else {
    this.setState(state => ({
      isVisible: state.isVisible
    }));
  }
};