Uncaught TypeError: Cannot read property 'state' of undefined - React

Question

I can not figure out if I am missing something small here?

Just trying to get a grasp on how state works with React.

Just creating a small check box that change

Answer 1

Changes:

1. You forgot to bind the onChange method, either use this:

onChange={this.handleCheck.bind(this)}

or define the binding in the constructor:

this.handleCheck = this.handleCheck.bind(this)

2. You used setState in a wrong way, setState is a method you need to call it.

Instead of: this.setState = ({})

it should be: this.setState({})

Answer 2

Binding your handleCheck function in the constructor:

constructor(props) {
    super(props);

    this.state = {
        checked: true
    };

    this.handleCheck = this.handleCheck.bind(this);
}