What will happen if I use setState() function in constructor of a Class in ReactJS or React Native?

Question

Out of curiosity, I just wanna know what will happen if I use setState() function in constructor of a Class in React Native or ReactJS? Such as:

Answer 1

Error Message would be Uncaught TypeError: Cannot read property 'VARIABLE_NAME' of null

Please see the following two jsfiddle snippets.

Case 1) Working solution jsfiddle

class Hello extends React.Component {
    constructor(props) {
      super(props);

      this.state = {
        name: 'world'
      } 
    }

  render() {
    return 
{this.state.name} 
  }
}

ReactDOM.render(, document.getElementById('container'));

Case 2) Not working solution

class Hello extends React.Component {
    constructor(props) {
      super(props);

      this.setState({
        name: 'hello'
      });
    }

  render() {
    return 
{this.state.name} 
  }
}

ReactDOM.render(, document.getElementById('container'));

Conclusion:

My rule of thumb, inside constructor uses this.state = {} directly, other places use this.setState({ });